Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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High-count rate photon detection with scintillators coupled to photomultiplier tubes and fast digitizers
García Rivas, I.; Fernández Prieto, A.; Kögler, T.; Römer, K.; Hueso González, F.
Abstract
This repository contains raw experimental data acquired during the gELBE beam time performed in October 2023 under proposal number 23203137-ST, at Helmholtz-Zentrum Dresden - Rossendorf.
In this setup, a bremsstrahlung beam of up to 12.5 MeV energy in 13 MHz pulses irradiates a CeBr3 scintillation detector (by Hilger®) of Ø 1'' x 1'', coupled to a Hamamatsu® R13408-100 PMT, custom voltage divider and shaping electronics, and a commercial digitizer (SFMC01+SIS1160) by Struck®, containing an AD9689 chip that supports a data sampling rate of 2.5 Gsps and 14-bits. This detector is developed in the context of the coaxial prompt gamma-ray monitoring method [1], where very high count rates are expected [2]. The dead-time-free data acquisition is programmed in-house using ROOT [3]. In addition, a plastic scintillation detector (paddle) was placed inbetween the beam and the CeBr3 crystal to serve as reference beam monitor. An Arduino is used to monitor the high-voltage supply for the PMT and active divider electronics in terms of current, voltage and temperature. A Comet Systems® T7310 is used to monitor ambient temperature, humidity and pressure.
The published data consist of the raw signal waveforms acquired during ~450 measurements. Each measurement is stored in a separate folder, its name being the acquisition time start, and lasts between 3 and 20 seconds (16 GiB up to 100 GiB). The data format is little-endian binary. Each sample uses two bytes, being the 14 first bits the digitized signal in a 1.7 Vpp range, and the 15th bit the (negated) logic status of the reference beam monitor (paddle). Samples are stored consecutively, without headers. Sample time separation is 0.4 ns (2.5 Gsps). The digitizer is phase-locked to the accelerator radiofrequency (RF), so that each 2500 stored samples correspond to 13 consecutive periods of 13 MHz.
The data can be directly opened using the open-source pulse visualization software (PulseSurfer) available in this link: https://igit.ific.uv.es/ferhue/pulse-surfer/, with ROOT as a dependency. One just needs to run:
root -l test_gui.cpp+(\"/path-to-folder/chA.bin\")
and then set 192.307692307692307696 in the "Cycle" box. Use the slider in the bottom to navigate across different consecutive frames. To visualize the paddle counter (negated) logic status, change the "Mask" box from 3FFF to 4000. There is also a checkbox to activate the baseline subtraction.
In addition to the raw waveform data (chA.bin), each folder contains following metadata:
- log.root a ROOT file storing all the measurement and hardware settings as TObjString. It also contains the T7310 monitoring as a TTree ("pth")
- chA.root a ROOT file storing a TTree that benchmarks the readout speed of the DAQ for this channel
- zdt.log a text file storing the output printed by the DAQ software to terminal
- gui.png Screenshot of the DAQ window
- hv.txt a test file storing the monitoring of the high-voltage supply and electronics
Keywords: Proton Therapy; Range Verification; High-count rate photon detection; high speed digitizers; pile-up deconvolution
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- γ-ELBE DOI: 10.58065/24020
Related publications
- DOI: 10.58065/24020 is cited by this (Id 39098) publication
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 39098) publication
- DOI: 10.1016/j.nima.2018.09.062 is referenced by this (Id 39098) publication
- DOI: 10.1016/j.sna.2023.114859 is referenced by this (Id 39098) publication
- DOI: 10.1016/j.nima.2022.166701 is referenced by this (Id 39098) publication
- DOI: 10.1088/1361-6560/ab176d is referenced by this (Id 39098) publication
- DOI: 10.1109/JSEN.2021.3062428 is referenced by this (Id 39098) publication
- DOI: 10.1109/TRPMS.2019.2930362 is referenced by this (Id 39098) publication
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-16 Open access
DOI: 10.14278/rodare.2806
Versions: 10.14278/rodare.2807
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-39098
Software engineering for validating finite-temperature XC-functional
Lokamani, M.; Ramakrishna, K.; Hüser, C.; Huste, T.; Cangi, A.; Juckeland, G.
Abstract
In recent years, density functional theory (DFT) has revolutionzed simulations in the domain of warm dense matter (WDM) which focuses on unraveling behavior of matter in fusion reactor, planetary interiors and other areas of high energy physics. The success of DFT relies on accurate approximations of the exchange-correlation (XC) effects based on exact quantum monte carlo (QMC) results. In this contribution, we summarize our recent work toward improving XC at finite temperatures, which is called thermal PBE[1] and incorporting the improvements in LIBXC[2], a library widely used in the material science community. We highlight the software engineering challenges in the field of high performance computing including: (i) deployment of continuous integration (CI) using Gitlab runners, (ii) incorporating containers for CI and reproducibility and (iii) refactoring strategies. We also highlight the importance of research software engineering (RSE) for validating accurate utilization of community high-performance-computing codes.
References
[1] https://doi.org/10.48550/arXiv.2308.03319
[2] https://doi.org/10.1016/j.softx.2017.11.002
Keywords: density functional theory; EVERSE; thermalPBE; research software engineering
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Lecture (Conference)
RSEHPC@ISC24, 12.-16.05.2024, Hamburg, Germany
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Permalink: https://www.hzdr.de/publications/Publ-39096
Quantum critical fluctuations in a transverse-field Ising magnet
Hauspurg, A.; Matsuura, K.; Arima, T.; Zherlitsyn, S.; Wosnitza, J.
Abstract
CoNb2O6 is a model system for a spin-1/2 one-dimensional (1D) transverse-field Ising magnet (TFIM) with a rather low three-dimensional (3D) Néel ordering temperature at TN = 2.95 K. We studied CoNb2O6 using ultrasound measurements down to 0.3 K in transverse magnetic fields applied along the b direction. Upon entering the 3D ordered state, we observe pronounced anomalies in the transverse acoustic mode c66. In particular, from 1.3 to 1.5 K and around 4.7 T, this mode reveals an almost diverging softening, which is considerably reduced at lower and higher magnetic fields. We interpret this as an influence of quantum critical fluctuations emerging from the quantum critical point (QCP) of the 1D Ising spin chains at about 4.75 T, which lies below the QCP of the 3D ordering at about 5.4 T. This is clear experimental evidence of the predicted generic phase diagram for a TFIM with superimposed 3D ordering.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Journal of Physics: Condensed Matter 36(2024), 325801
DOI: 10.1088/1361-648X/ad44fc
Permalink: https://www.hzdr.de/publications/Publ-39089
Fractionalized excitations probed by ultrasound
Hauspurg, A.; Zherlitsyn, S.; Helm, T.; Felea, V.; Wosnitza, J.; Tsurkan, V.; Choi, K.-Y.; Do, S.-H.; Ye, M.; Brenig, W.; Perkins, N. B.
Abstract
In this work, we study magnetoelastic interactions by means of ultrasound experiments in α-RuCl3—a prototypical material for the Kitaev spin model on the honeycomb lattice, with a possible spin-liquid state featuring Majorana fermions and Z2-flux excitations. We present results of the temperature and in-plane magnetic-field dependence of the sound velocity and sound attenuation for several longitudinal and transverse phonon modes propagating along high-symmetry crystallographic directions. A comprehensive data analysis above the magnetically ordered state provides strong evidence of phonon scattering by Majorana fermions. This scattering depends sensitively on the value of the phonon velocities relative to the characteristic velocity of the low-energy fermionic excitations describing the spin dynamics of the underlying Kitaev magnet. Moreover, our data displays a distinct reduction of anisotropy of the sound attenuation, consistent with the presence of thermally excited Z2 visons. We demonstrate the potential of phonon dynamics as a promising probe for uncovering fractionalized excitations in α-RuCl3 and provide new insights into the H-T phase diagram of this material.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Physical Review B 109(2024), 144415
DOI: 10.1103/PhysRevB.109.144415
arXiv: arXiv:2303.09288
Downloads
- Open Access Version from arxiv.org
- Secondary publication expected from 18.04.2025
Permalink: https://www.hzdr.de/publications/Publ-39088
Narrowly avoided spin-nematic phase in BaCdVO(PO4)2: NMR evidence
Ranjith, K. M.; Povarov, K.; Yan, Z.; Zheludev, A.; Horvatic, M.
Abstract
We present a 31P NMR investigation of BaCdVO(PO4)2 focusing on the nearly saturated regime between μ0Hc1 = 4.05 T and μ0Hc2 = 6.5 T, which used to be considered a promising candidate for a spin-nematic phase. NMR spectra establish the absence of any dipolar order there, whereas the weak field dependence of the magnetization above Hc1 is accounted for by Dzyaloshinskii-Moriya interaction terms. The low-energy spin dynamics (fluctuations), measured by the nuclear spin-lattice relaxation rate T1
−1, confirms the continuity of this phase and the absence of any low-temperature phase transition. Unexpectedly, the spin dynamics above Hc1 is largely dominated by two-magnon processes, which is expected above the saturation field of a spin-nematic phase, but not inside. This shows that BaCdVO(PO4)2 is indeed close to a spin-nematic instability; however, this phase is not stabilized. We thus confirm recent theoretical predictions that the spin-nematic phase can be stabilized, at most, in an extremely narrow field range close to saturation or is rather narrowly avoided [Jiang et al., Phys. Rev. Lett. 130, 116701 (2023)].
Involved research facilities
- High Magnetic Field Laboratory (HLD)
-
Physical Review Research 6(2024), 023043
DOI: 10.1103/PhysRevResearch.6.023043
Permalink: https://www.hzdr.de/publications/Publ-39087
Data publication: Defect Microstructure Evolution in Immiscible Composite Cu43%Cr Alloy after High-Pressure Torsion and Annealing using Positron Annihilation Spectroscopy
Bibimoune, I.; Hirschmann, E.; Liedke, M. O.; Wagner, A.; Kawasaki, M.; Baudin, T.; Mkinsi, I.; Abib, K.; Huang, Y.; Langdon, T. G.; Bradai, D.
Abstract
This data set contains positron annihilation lifetime spectra and VEPAS-DB spectra. It contains raw data and the corresponding analyzed data.
Keywords: Cu-Cr; immiscible alloys; high-pressure torsion; defects; positron annihilation spectroscopy
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-05-13 Closed access
DOI: 10.14278/rodare.2859
Versions: 10.14278/rodare.2860
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Permalink: https://www.hzdr.de/publications/Publ-39080
A matter of performance & criticality: a review of rare-earth-based magnetocaloric intermetallic compounds for hydrogen liquefaction
Liu, W.; Gottschall, T.; Scheibel, F.; Bykov, E.; Aubert, A.; Fortunato, N.; Beckmann, B.; Döring, A. M.; Zhang, H.; Skokov, K.; Gutfleisch, O.
Abstract
The low efficiency of conventional liquefaction technologies based on the Joule-Thomson expansion makes liquid hydrogen currently not attractive enough for large-scale energy-related technologies that are important for the transition to a carbon-neutral society. Magnetocaloric hydrogen liquefaction has great potential to achieve higher efficiency and is therefore a crucial enabler for affordable liquid hydrogen. Cost-effective magnetocaloric materials with large magnetic entropy and adiabatic temperature changes in the temperature range of 77 ∼ 20 K under commercially practicable magnetic fields are the foundation for the success of magnetocaloric hydrogen liquefaction. Heavy rare-earth-based magnetocaloric intermetallic compounds generally show excellent magnetocaloric performances, but the heavy rare-earth elements (Gd, Tb, Dy, Ho, Er, and Tm) are highly critical in resources. Yttrium and light rare-earth elements (La, Ce, Pr, and Nd) are relatively abundant, but their alloys generally show less excellent magnetocaloric properties. A dilemma appears: higher performance or lower criticality? In this review, we study how cryogenic temperature influences magnetocaloric performance by first reviewing heavy rare-earth-based intermetallic compounds. Next, we look at light rare-earth-based, "mixed" rare-earth-based, and Gd-based intermetallic compounds with the nature of the phase transition order taken into consideration, and summarize ways to resolve the dilemma.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
-
Journal of Alloys and Compounds 995(2024), 174612
DOI: 10.1016/j.jallcom.2024.174612
arXiv: https://arxiv.org/abs/2405.01128
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Permalink: https://www.hzdr.de/publications/Publ-39076
Data publication: Defectivity of Al:ZnO Thin Films with Different Crystalline Order Probed by Positron Annihilation Spectroscopy
Magrin Maffei, R.; Butterling, M.; Liedke, M. O.; D’Addato, S.; Di Bona, A.; Bertoni, G.; Gazzadi, G. C.; Mariazzi, S.; Wagner, A.; Brusa, R. S.; Benedetti, S.
Abstract
Positronen-Lebensdauer-Messungen gewonnen an der Positronen-Strahlanlage MePS (pELBE), August 2023 Doppler-Verbreiterungs-Messungen gewonnen an der Positronen-Strahlanlage SPONSOR (pELBE), September 2023
Keywords: Positron Annihilation; MePS; SPONSOR; AZO; AlZnO; PALS; VEPALS; VEPAS
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- P-ELBE
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 39072) publication
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-05-08 Closed access
DOI: 10.14278/rodare.2857
Versions: 10.14278/rodare.2858
Downloads
Permalink: https://www.hzdr.de/publications/Publ-39072
Simplified Beam Hardening Correction for Ultrafast X-ray CT Imaging of Binary Granular Mixtures
Bieberle, M.; Nestor Papapetrou, T.; Lecrivain, G.; Windisch, D.; Bieberle, A.; Wagner, M.; Hampel, U.
Abstract
Ultrafast X-ray computed tomography is an advanced imaging technique for multiphase flows. It has been used with great success for studying gas–liquid as well as gas–solid flows. Here, we apply this technique to analyze density-driven particle segregation in a rotating drum as an exemplary use case for analyzing industrial particle mixing systems. As glass particles are used as the denser of two granular species to be mixed, beam hardening artefacts occur and hamper the data analysis. In the general case of a distribution of arbitrary materials, the inverse problem of image reconstruction with energy-dependent attenuation is often ill-posed. Consequently, commonly known beam hardening correction algorithms are often quite complex. In our case, however, the number of materials is limited. We therefore propose a correction algorithm simplified by taking advantage of the known material properties, and demonstrate its ability to improve image quality and subsequent analyses significantly.
Keywords: beam hardening; computed tomography; image reconstruction; ultrafast measurement; granular media; particle mixing; rotating drum
Involved research facilities
- ROFEX
Related publications
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Data and code: Investigating binary granular mixing in a rotating drum using …
ROBIS: 36765 HZDR-primary research data are used by this (Id 39067) publication -
Data and code: Investigating binary granular mixing in a rotating drum using …
RODARE: 2505 HZDR-primary research data are used by this (Id 39067) publication
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Sensors 24(2024), 2964
DOI: 10.3390/s24102964
Permalink: https://www.hzdr.de/publications/Publ-39067
Control of the Hydroquinone/Benzoquinone Redox State in High-Mobility Semiconducting Conjugated Coordination Polymers
Huang, X.; Li, Y.; Fu, S.; Ma, C.; Lu, Y.; Wang, M.; Zhang, P.; Li, Z.; He, F.; Huang, C.; Liao, Z.; Zou, Y.; Zhou, S.; Helm, M.; Petkov, P. S.; Wang, H. I.; Bonn, M.; Li, J.; Xu, W.; Dong, R.; Feng, X.
Abstract
Conjugated coordination polymers (c-CPs) are unique organic–inorganic hybrid semiconductors with intrinsically high electrical conductivity and excellent charge carrier mobility. However, it remains a challenge in tailoring electronic structures, due to the lack of clear guidelines. Here, we develop a strategy wherein controlling the redox state of hydroquinone/benzoquinone (HQ/BQ) ligands allows for the modulation of the electronic structure of c-CPs while maintaining the structural topology. The redox-state control is achieved by reacting the ligand TTHQ (TTHQ=1,2,4,5-tetrathiolhydroquinone) with silver acetate and silver nitrate, yielding Ag4TTHQ and Ag4TTBQ (TTBQ=1,2,4,5-tetrathiolbenzoquinone), respectively. In spite of sharing the same topology consisting of a two-dimensional Ag−S network and HQ/BQ layer, they exhibit different band gaps (1.5 eV for Ag4TTHQ and 0.5 eV for Ag4TTBQ) and conductivities (0.4 S/cm for Ag4TTHQ and 10 S/cm for Ag4TTBQ). DFT calculations reveal that these differences arise from the ligand oxidation state inhibiting energy band formation near the Fermi level in Ag4TTHQ. Consequently, Ag4TTHQ displays a high Seebeck coefficient of 330 μV/K and a power factor of 10 μW/m ⋅ K2, surpassing Ag4TTBQ and the other reported silver-based c-CPs. Furthermore, terahertz spectroscopy demonstrates high charge mobilities exceeding 130 cm2/V ⋅ s in both Ag4TTHQ and Ag4TTBQ.
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Angewandte Chemie - International Edition 63(2024), e202320091
DOI: 10.1002/anie.202320091
Permalink: https://www.hzdr.de/publications/Publ-39064
Data publication: Static and dynamic properties of noncollinear magnetized ferromagnetic films
Jiménez-Bustamante, J.; Lindner, A. A.; Koyun Yücel, H. N.; Salikhov, R.; Lenz, K.; Lindner, J.; Gallardo, R. A.
Abstract
Research data of the publication (FMR, VSM).
Related publications
- DOI: 10.1103/PhysRevB.109.094403 references this (Id 39062) publication
-
Static and dynamic properties of noncollinear magnetized ferromagnetic films
ROBIS: 39061 has used this (Id 39062) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-05-07 Closed access
DOI: 10.14278/rodare.2853
Versions: 10.14278/rodare.2854
Downloads
Permalink: https://www.hzdr.de/publications/Publ-39062
Static and dynamic properties of noncollinear magnetized ferromagnetic films
Jiménez-Bustamante, J.; Lindner, A. A.; Koyun Yücel, H. N.; Salikhov, R.; Lenz, K.; Lindner, J.; Gallardo, R. A.
Abstract
The dynamic matrix method was employed to perform theoretical calculations for investigating both static and
dynamic characteristics of thick ferromagnetic films. This approach considers situations where a noncollinear
equilibrium magnetization exists along the thickness due to a thickness-dependent uniaxial anisotropy and inter-
facial interactions in a synthetic antiferromagnet. In the former scenario, the study exposes a correlation between
noncollinear static magnetization and a nonmonotonic dependence of ferromagnetic resonance frequency, where
a frequency decrease is observed at low fields in the unsaturated regime. Regarding the synthetic antiferromagnet
structure, the research demonstrates noncoherent magnetization rotation in the spin-flop regime, with twisted
magnetization states influencing the critical and nucleation fields that define the spin-flop region. The results of
the investigation were compared to the macrospin approach, where the magnetization is assumed to be uniform
along the thickness. The study suggests that the contribution of noncollinear magnetic moments may mimic the
role of the biquadratic interaction in the macrospin model, implying that such a biquadratic term may be over-
estimated in coupled ferromagnetic films with thicknesses exceeding the material’s intrinsic exchange length.
Finally, the model was compared with experimental data obtained from a Py/Ir/Py synthetic antiferromagnet,
demonstrating that the theoretical consideration of a twisting equilibrium state of the magnetization precisely
reproduces the observed dynamic and static properties of the nanostructure.
Related publications
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Data publication: Static and dynamic properties of noncollinear magnetized …
ROBIS: 39062 HZDR-primary research data are used by this (Id 39061) publication
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Physical Review B 109(2024), 094403
DOI: 10.1103/PhysRevB.109.094403
Downloads
- Secondary publication expected from 04.03.2025
Permalink: https://www.hzdr.de/publications/Publ-39061
Tailoring dielectric permittivity of epitaxial Gd-doped CeO2−x films by ionic defects
Palliotto, A.; Wu, Y.; Rata, A. D.; Herklotz, A.; Zhou, S.; Dörr, K.; Muralt, P.; Park, D.-S.
Abstract
Engineering materials with highly tunable physical properties in response to external stimuli is a cornerstone strategy for advancing energy technology. Among various approaches, engineering ionic defects and understanding their roles are essential in tailoring emergent material properties and functionalities. Here, we demonstrate an effective approach for creating and controlling ionic defects (oxygen vacancies) in epitaxial Gd-doped CeO2−x (CGO)(001) films grown on Nb:SrTiO3(001) single crystal. Our results exhibit a significant limitation in the formation of excess oxygen vacancies in the films during high-temperature film growth. However, we have discovered that managing the oxygen vacancies in the epitaxial CGO(001) films is feasible using a two-step film growth process. Subsequently, our findings show that manipulating excess oxygen vacancies is a key to the emergence of giant apparent dielectric permittivity (e.g. 106) in the epitaxial films under electrical field control. Overall, the strategy of tuning functional ionic defects in CGO and similar oxides is beneficial for various applications such as electromechanical, sensing, and energy storage applications.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39052) publication
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Journal of Physics: Energy 6(2024), 025005
DOI: 10.1088/2515-7655/ad2452
Permalink: https://www.hzdr.de/publications/Publ-39052
Data publication: Risk assessment for Na-Zn liquid metal batteries
Weber, N.; Duczek, C.; Monrrabal Marquez, G.; Nash, W.; Sarma, M.; Weier, T.
Abstract
The dataset contains the risk assessment table as well as certain calculations.
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-05-03 Open access
DOI: 10.14278/rodare.2851
Versions: 10.14278/rodare.2852
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-39047
Depth-distribution of resistivity within ion-irradiated semiconductor layers revealed by low-kV scanning electron microscopy
Jóźwik, I.; Jagielski, J.; Ciepielewski, P.; Dumiszewska, E.; Piętak-Jurczak, K.; Kamiński, M.; Kentsch, U.
Abstract
Low-kV scanning electron microscopy imaging was used to visualize the 2D profiles of internal resistivity distribution in 600 keV He2+ ion-irradiated epitaxial GaAs and Al(0.55)Ga(0.45)As. The influence of the dopant concentration on DIVA (damage-induced voltage alteration) contrast formation has been studied in this paper. The threshold irradiation fluencies (the fluencies below which no damage-related contrast is observed) were defined for each studied material. The results show that the same level of damage in the material caused by ion irradiation becomes visible at lower threshold fluence in the case of lower-doped sample of the same composition. The aluminum content in the composition of materials exposed to ion irradiation and subsequent DIVA contrast formation mechanism was considered as well. The carrier concentration in irradiated layers has been studied by Raman spectroscopy and photoluminescence measurements, which confirmed that the increase of the resistivity of the material caused by ion-irradiation damage generation is resulting from the formation of deep states in the bandgap trapping free carriers.
Keywords: AIIIBV; Ion damage; Low-kV SEM
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39046) publication
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Materials Science in Semiconductor Processing 165(2023), 107640
DOI: 10.1016/j.mssp.2023.107640
Permalink: https://www.hzdr.de/publications/Publ-39046
Approaching the Curie temperature of ferromagnetic (Ga,Mn)P prepared by ion implantation and pulsed laser melting
Tian, M.; Yang, Q.; Yuan, Y.; Kentsch, U.; Liu, K.; Tang, M.; Xie, Z.; Li, L.; Wang, M.
Abstract
This work aims to estimate the Curie temperature and critical exponents in the critical regime of III-V ferro- magnetic semiconductor (FS) (Ga,Mn)P film using various methods, including Arrott and Kouvel-Fisher plots, as well as electrical transport measurements. The (Ga,Mn)P film was prepared by implanting Mn ions into an intrinsic (001) GaP wafer, followed by pulsed laser melting (PLM). The magnetic properties of the (Ga,Mn)P layer were systematically investigated. The study investigated the accuracy of four different methods in deter- mining the critical behaviors for the magnetic properties close to TC. The results suggest that the critical ex- ponents are similar to those of the mean-field model, as indicated by the modified Arrot plots and temperature dependent effective critical exponents. However, the accuracy of the temperature-dependent resistance Rₓₓ(T) method and Kouvel-Fisher (K-F) analysis is limited due to the Gaussian distribution of Mn ions in the film.
Keywords: Magnetic properties; Ion implantation; Electrical transport; Ferromagnetic; III-V ferromagnetic semiconductors
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39045) publication
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Results in Physics 58(2024), 107508
DOI: 10.1016/j.rinp.2024.107508
Permalink: https://www.hzdr.de/publications/Publ-39045
Prior implantation of hydrogen as a mechanism to delay helium bubbles, blistering, and exfoliation in titanium
Fink Ilyasafov, S.; Maman, N.; Kentsch, U.; Zenou, V. Y.; Vaknin, M.; Rakita, Y.; Zamir, G.; Dahan, I.; Shneck, R. Z.
Abstract
This study explores the delaying of the formation of helium bubbles and blisters in pure titanium by hydrogen pre-implantation. Titanium, implanted with helium (40 KeV, 5 × 10¹⁷ ions/cm²), exhibited large bubbles that cause exfoliation after heat treatment, whereas hydrogen pre-implantation inhibited bubble growth at room temperature and reduced the exfoliation after heat treatment.
In the samples pre-implanted with hydrogen, we found evidence of helium diffusion delay by: (a) a fourfold reduction in bubble pressure (b) faceted cavities in the samples (c) a smaller increase in titanium lattice pa- rameters (d) a 16-fold reduction in average bubble size and a sixfold reduction in bubble area fraction (e) a more than twofold decrease in exfoliation (f) a tendency toward the formation of larger bubbles as a result of heat treatment. We believe that it is reasonable to assume that the inhibition of helium diffusion between tetrahedral interstitial lattice sites takes place because of the occupation of the intermediate octahedral sites by hydrogen atoms.
Evidence for the opposite effect, that is inhibition of the diffusion of hydrogen in the presence of helium, is found in the retention of hydrogen in the specimens at elevated temperatures. This retention allowed the exis- tence of titanium hydride after heat treatment at 680 °C. The present study sheds light on the intricate interplay between hydrogen and helium in titanium, providing insights into mechanisms that can potentially mitigate helium-induced damage in materials.
Keywords: Bubble formation; Helium implantation; Pre-implantation; Plasma-facing materials (PFMs); Nuclear technology; Irradiation damage; Helium diffusion; Titanium hydride; Blisters; Surface exfoliation; Repulsive interactions; EELS
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39044) publication
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Journal of Nuclear Materials 594(2024), 155017
DOI: 10.1016/j.jnucmat.2024.155017
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- Secondary publication expected from 13.03.2025
Permalink: https://www.hzdr.de/publications/Publ-39044
Sublimed fine-grained dysprosium: Significant magnetocaloric effect
Koshkidko, Y. S.; Cwik, J.; Salazar Mejia, C.; Dormidontov, N. A.; Prokofev, P. A.; Bakulina, A. S.; Nikitin, A. A.; Khomich, A. A.; Gimaev, R. R.; Andreenko, A. S.; Burmii, Z. P.; Telitsa, A. A.; Zverev, V. I.; Kolchugina, N. B.
Abstract
As is known, rare-earth metals (REMs) are promising magnetocaloric materials. The magnitude of the magnetocaloric effect (MCE) of REMs significantly depends on their purity. This paper presents results of studies of the magnetic and magnetocaloric properties of sublimed dysprosium, prepared in the course of the present study, with an emphasis on its impurity and structure perfection. The comprehensive analysis of the chemical composition of sublimed dysprosium, which was performed for the first time by atom probe tomography, showed that the metal corresponds to high-purity rare-earth metals (3 N+). The MCE effect was studied using direct measurements of the adiabatic temperature change (ΔTad) in pulsed (up to 50 T) and steady (up to 14 T) magnetic fields. The studies of the MCE of polycrystalline sublimed Dy by direct method showed that the high ΔTad value for sublimed Dy are comparable with those obtained for single-crystal Dy in magnetic fields up to 5 T. The vacuum sublimation, which is more economical and technologically advanced in contrast to single crystal growing, can be used to create magnetocaloric REM-based materials with high MCE values.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Vacuum 225(2024), 113239
DOI: 10.1016/j.vacuum.2024.113239
Permalink: https://www.hzdr.de/publications/Publ-39042
A Co(II)-Hydroxide Complex That Converts Directly to a Co(II)-Acetamide during Catalytic Nitrile Hydration
Heim, P.; Biswas, S.; Lopez, H.; Gericke, R.; Twamley, B.; McDonald, A. R.
Abstract
In exploring structural and functional mimics of nitrile hydratases, we report the synthesis of the pseudo-trigonal bipyramidal Co(II) complexes (K)[Co(II)(DMF)(LPh)] (1(DMF)), (NMe₄)₂[Co(II)(OAc)(LPh)] (1(OAc)), and (NMe₄)₂[Co(II)(OH)(LPh)] (1(OH)) (LPh = 2,2′,2’’-nitrilo-tris-(N-phenylacetamide; DMF = N,N-dimethylformamide; −OAc = acetate)). The complexes were characterized using NMR, FT-IR, ESI-MS, electronic absorption spectroscopy, and X-ray crystallography, showing the LPh ligand to bind in a tetradentate tripodal fashion alongside the respective ancillary donor. One of the complexes, 1(OH), is an unusual structural and functional mimic of the Co active site in Co nitrile hydratases. 1(OH) reacted with acetonitrile to yield the Co(II)-acetamide complex (NMe₄)₂[Co(II)(NHC(O)CH₃)(LPh)], 2, which was also thoroughly characterized. In the presence of excess hydroxide, 1(OH) was found to catalyze quantitative conversion of the added hydroxide into acetamide. Despite the differences in Co oxidation state in nitrile hydratases and 1(OH) (Co(III) versus Co(II), respectively), 1(OH) was nonetheless an effective nitrile hydration catalyst, selectively producing acetamide over multiple turnovers.
Keywords: Anions; Hydration; Ions; Ligands; Nitrogen compounds
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Inorganic Chemistry 63(2024), 7896-7902
DOI: 10.1021/acs.inorgchem.4c00754
Permalink: https://www.hzdr.de/publications/Publ-39041
Irradiation-induced enhancement of Fe and Al magnetic polarizations in Fe60Al40 films
Smekhova, A.; Szyjka, T.; La Torre, E.; Ollefs, K.; Eggert, B.; Cöster, B.; Wilhelm, F.; Bali, R.; Lindner, J.; Rogalev, A.; Többens, D.; Weschke, E.; Luo, C.; Chen, K.; Radu, F.; Schmitz-Antoniak, C.; Wende, H.
Abstract
The rise of Fe magnetic moment, changes in Al electronic structure and a variation of Al magnetic polarization in thin films of transition metal aluminide Fe60Al40 have been probed through the order-disorder phase transition by soft x-ray absorption spectroscopy and x-ray resonant magnetic reflectivity in the extreme ultraviolet regime. In a course of the transition induced by 20 keV Ne+ irradiation with low fluences (∼1014 ions cm−2), x-ray magnetic circular dichroism spectra taken at the Fe L2,3 absorption edges at room and low temperatures revealed a pronounced increase of Fe 3d states spin-polarization. X-ray resonant magnetic reflectivity applied to the Al L2,3 and Fe M2,3 edges allowed to detect the magnetic polarization of Al atoms in the films. The changes in Al electronic structure have been seen by alteration of Al K edge x-ray absorption near edge structure. A difference in anisotropy fields for films before and after irradiation has been observed by element-specific hysteresis loops recorded at low temperatures in absorption and reflection geometries at the Fe L2,3 and M2,3 edges, respectively. An attempt to reduce the top oxide layer by an inductively coupled hydrogen plasma has shown a possibility to recover the chemically ordered
phase.
Keywords: chemical disorder; ion-irradiation; XANES; XMCD; plasma treatment
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39038) publication
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New Journal of Physics 26(2024), 023036
DOI: 10.1088/1367-2630/ad1497
Permalink: https://www.hzdr.de/publications/Publ-39038
Chains of atoms embedded into transition metal dichalcogenides as one-dimensional half-metallic magnets
Davies, F. H.; Krasheninnikov, A.
Abstract
Quasi-one-dimensional structures, single chains of Pt and Co atoms embedded into mirror twin boundaries in two-dimensional MoS2, have recently been fabricated [Guo et al., Nat. Synth. 1, 245 (2022)]. Using both collinear and noncollinear first-principles calculations, we predict that other transition metals can form similar structures, and that these systems should possess exciting electronic and magnetic properties and specifically exhibit half-metallic electronic behavior. We further analyze the magnetocrystalline anisotropy of these systems and show that they possess unique easy axes and varying strengths of anisotropy, making thus efficient magneti- zation switching possible. We finally discuss the potentials of using single-atom chains embedded in MoS2 and other transition metal dichalcogenides in spintronic devices.
Keywords: 2D materials; Atomic chains; First-principles calculations
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39036) publication
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Physical Review B 109(2024), 165442
DOI: 10.1103/PhysRevB.109.165442
Downloads
- Secondary publication expected from 30.04.2025
Permalink: https://www.hzdr.de/publications/Publ-39036
Robust Magnetoelectric Coupling in FeTiO3/Ga2O3 Non-van der Waals Heterostructures
Jin, C.; Tang, X.; Sun, Q.; Mu, C.; Krasheninnikov, A.; Kou, L.
Abstract
Magnetoelectric coupling represents a significant breakthrough for next-generation electronics, offering the ability to achieve nonvolatile magnetic control via electrical means. In this comprehensive investigation, leveraging first-principles calculations, we unveil a robust magnetoelectric coupling within multiferroic heterostructures (HSs) by ingeniously integrating a non-van der Waals (non-vdW) magnetic FeTiO3 monolayer with the ferroelectric (FE) Ga2O3. Diverging from conventional van der Waals (vdW) multiferroic HSs, the magnetic states of the FeTiO3 monolayer can be efficiently toggled between ferromagnetic (FM) and antiferromagnetic (AFM) configurations by reversing the polarization of the Ga2O3 monolayer. This intriguing phenomenon arises from polarization-dependent substantial interlayer electron transfers and the interplay between superexchange and direct-exchange magnetic couplings of the iron atoms. The carrier-mediated interfacial interactions induce crucial shifts in Fermi level positions, decisively imparting distinct electronic characteristics near the Fermi level of composite systems. These novel findings offer exciting prospects for the future of magnetoelectric technology.
Keywords: 2D materials; Heterostructures; First-principles calculations
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39035) publication
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The Journal of Physical Chemistry Letters 15(2024), 2650-2657
DOI: 10.1021/acs.jpclett.4c00029
Downloads
- Secondary publication expected from 28.02.2025
Permalink: https://www.hzdr.de/publications/Publ-39035
A priori procedure to establish spinodal decomposition in alloys
Divilov, S.; Eckert, H.; Toher, C.; Friedrich, R.; Zettel, A. C.; Brenner, D. W.; Fahrenholtz, W. G.; Wolfe, D. E.; Zurek, E.; Maria, J.-P.; Hotz, N.; Campilongo, X.; Curtarolo, S.
Abstract
Spinodal decomposition can improve a number of essential properties in materials, especially hardness. Yet,
the theoretical prediction of the onset of this phenomenon (e.g., temperature) and its microstructure (e.g.,
wavelength) often requires input parameters coming from costly and time-consuming experimental efforts,
hindering rational materials optimization. Here, we present a procedure where such parameters are not derived
from experiments. First, we calculate the spinodal temperature by modeling nucleation in the solid solution
while approaching the spinode boundary. Then, we compute the spinodal wavelength self-consistently using
a few reasonable approximations. Our results show remarkable agreement with experiments and, for NiRh,
the calculated yield strength due to spinodal microstructures surpasses even those of Ni-based superalloys.
We believe that this procedure will accelerate the exploration of the complex materials experiencing spinodal
decomposition, critical for their macroscopic properties.
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Acta Materialia 266(2024), 119667
DOI: 10.1016/j.actamat.2024.119667
Downloads
Permalink: https://www.hzdr.de/publications/Publ-39034
Charge Collection Efficiency of Single GaN Core-Shell Wires Assessed by High-Precision Ion-Beam-Induced Charge Measurements
Verheij, D.; Vićentijević, M.; Jakšić, M.; Peres, M.; Cerqueira Alves, L.; Cardoso, S.; Alves, E.; Durand, C.; Eymery, J.; Möller, W.; Lorenz, K.
Abstract
We report on the charge collection efficiency (CCE) of GaN core–shell p–n junction microwires obtained through high-precision ion-beam-induced charge (IBIC) measurements. Single wires are processed into working radiation detectors using a set of microfabrication processes and are irradiated with either 1 MeV or 750 keV Si ions. We show that we are able to accurately probe the microwires and measure structures that have dimensions below 1 μm. CCE maps show that the detectors are efficient in collecting the charge induced by the Si ions, presenting average CCE magnitudes between 20 and 30% when applying a small reverse bias. Additionally, three-dimensional Monte Carlo simulations were carried out to gain a better understanding of the energy deposition in the depletion region of the p–n junction. Comparison between the experimental and simulated data shows good agreement despite also revealing some drawbacks associated with the microwire detectors, namely, the poor collection efficiency of charge carriers generated in the neutral n-GaN core. Nevertheless, the average CCE of the detectors is promising, especially when only considering the energy deposited in the active region of the detector. In this case, depending on the applied bias, we obtain a CCE between 45 and 80%.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39030) publication
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ACS Applied Electronic Materials 6(2024)3, 1682-1692
DOI: 10.1021/acsaelm.3c01584
Permalink: https://www.hzdr.de/publications/Publ-39030
Formation and specific contact resistivity of NiGe on polycrystalline Ge made by flash lamp annealing
Begeza, V.; Rebohle, L.; Stöcker, H.; Mehner, E.; Hübner, R.; Zhou, S.
Abstract
Flash lamp annealing (FLA) is an ultra-short annealing method, which excellently meets the requirements of thinfilm processing and microelectronics. Due to the relatively high hole mobility, thin Ge layers are highly interesting as a transistor channel material or generally as a functional layer in CMOS technology and for low-cost electronics. One possibility to realize ohmic contacts with low contact resistance is the use of metal germanides, especially the stoichiometric NiGe phase. In this work, NiGe contacts on thin Ge films were fabricated by magnetron sputtering followed by FLA. The evolution of microstructure was traced by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Electrical measurements focused on the determination of contact resistance by the circular transfer length method. The contacts were fabricated by two different approaches, and the influence of different process steps on the layer morphology and uncertainty of the measurement was studied. Finally, we show that FLA as a thermal treatment with a low thermal budget is able to form NiGe on p-type Ge with a low contact resistance similar to that achieved by other thermal treatments.
Keywords: Germanium; Nickel germanide; Thin films; Sputtering; Flash lamp annealing; Circular transfer length method
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39029) publication
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Journal of Alloys and Compounds 990(2024), 174420
DOI: 10.1016/j.jallcom.2024.174420
Permalink: https://www.hzdr.de/publications/Publ-39029
Epigenetic Targeting to Overcome Radioresistance in Head and Neck Cancer
Schniewind, I.; José Besso, M.; Klicker, S.; Maria Schwarz, F.; Wijaya Hadiwikarta, W.; Richter, S.; Löck, S.; Linge, A.; Krause, M.; Dubrovska, A.; Baumann, M.; Kurth, I.; Peitzsch, C.
Abstract
(1) Background: The sensitivity of head and neck squamous cell carcinoma (HNSCC) to ionizing radiation, among others, is determined by the number of cells with high clonogenic potential and stem-like features. These cellular characteristics are dynamically regulated in response to treatment and may lead to an enrichment of radioresistant cells with a cancer stem cell (CSC) phenotype. Epigenetic mechanisms, particularly DNA and histone methylation, are key regulators of gene-specific transcription and cellular plasticity. Therefore, we hypothesized that specific epigenetic targeting may prevent irradiation-induced plasticity and may sensitize HNSCC cells to radiotherapy.
(2) Methods: We compared the DNA methylome and intracellular concentrations of tricarboxylic acid cycle metabolites in radioresistant FaDu and Cal33 cell lines with their parental controls, as well as aldehyde dehydrogenase (ALDH)-positive CSCs with negative controls. Moreover, we conducted a screen of a chemical library targeting enzymes involved in epigenetic regulation in combination with irradiation and analyzed the clonogenic potential, sphere formation, and DNA repair capacity to identify compounds with both radiosensitizing and CSC-targeting potential.
(3) Results: We identified the histone demethylase inhibitor GSK-J1, which targets UTX (KDM6A) and JMJD3 (KDM6B), leading to increased H3K27 trimethylation, heterochromatin formation, and gene silencing. The clonogenic survival assay after siRNA-mediated knock-down of both genes radiosensitized Cal33 and SAS cell lines. Moreover, high KDM6A expression in tissue sections of patients with HNSCC was associated with improved locoregional control after primary (n = 137) and post-operative (n = 187) radio/chemotherapy. Conversely, high KDM6B expression was a prognostic factor for reduced overall survival.
(4) Conclusions: Within this study, we investigated cellular and molecular mechanisms underlying irradiation-induced cellular plasticity, a key inducer of radioresistance, with a focus on
epigenetic alterations. We identified UTX (KDM6A) as a putative prognostic and therapeutic target for HNSCC patients treated with radiotherapy.
Keywords: histone methylation; radioresistance; cellular plasticity; cancer stem cells; head and neck cancer
Involved research facilities
- OncoRay
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Cancers 16(2024), 730
DOI: 10.3390/cancers16040730
Permalink: https://www.hzdr.de/publications/Publ-39024
Radiomics for residual tumour detection and prognosis in newly diagnosed glioblastoma based on postoperative [11C] methionine PET and T1c‑w MRI
Shahzadi, I.; Seidlitz, A.; Beuthien‑Baumann, B.; Zwanenburg, A.; Platzek, I.; Kotzerke, J.; Baumann, M.; Krause, M.; Troost, E. G. C.; Löck, S.
Abstract
Personalized treatment strategies based on non‑invasive biomarkers have potential to improve patient management in patients with newly diagnosed glioblastoma (GBM). The residual tumour burden after surgery in GBM patients is a prognostic imaging biomarker. However, in clinical patient management, its assessment is a manual and time‑consuming process that is at risk of inter‑rater variability. Furthermore, the prediction of patient outcome prior to radiotherapy may identify patient subgroups that could benefit from escalated radiotherapy doses. Therefore, in this study, we investigate the capabilities of traditional radiomics and 3D convolutional neural networks for automatic detection of the residual tumour status and to prognosticate time‑to‑recurrence (TTR) and overall survival (OS) in GBM using postoperative [11C] methionine positron emission tomography (MET‑PET) and gadolinium‑enhanced T1‑w magnetic resonance imaging (MRI). On the independent test data, the 3D‑DenseNet model based on MET‑PET achieved the best performance for residual tumour detection, while the logistic regression model with conventional radiomics features performed best for T1c‑w MRI (AUC: MET‑PET 0.95, T1c‑w MRI 0.78). For the prognosis of TTR and OS, the 3D‑DenseNet model based on MET‑PET integrated with age and MGMT status achieved the best performance (Concordance‑Index: TTR 0.68, OS 0.65). In conclusion, we showed that both deep‑
learning and conventional radiomics have potential value for supporting image‑based assessment and prognosis in GBM. After prospective validation, these models may be considered for treatment personalization.
Involved research facilities
- OncoRay
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Scientific Reports 14(2024), 4576
DOI: 10.1038/s41598-024-55092-8
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-39023
Data for: Experimental Analysis of Lifelines in a 15,000 L Bioreactor by Means of Lagrangian Sensor Particles
Hofmann, S.; Buntkiel, L.; Rautenbach, R.; Gaugler, L.; Ma, Y.; Haase, I.; Fitschen, J.; Wucherpfennig, T.; Reinecke, S.; Hoffmann, M.; Takors, R.; Hampel, U.; Schlüter, M.
Abstract
The DaRUS repository entails the raw files, result files and the MATLAB codes for the publication "Experimental Analysis of Lifelines in a 15,000 L Bioreactor by Means of Lagrangian Sensor Particles" in the journal "Chemical Engineering Research and Design".
This study employs Lagrangian Sensor Particles (LSPs) with a diameter of 40 mm equipped with a pressure sensor to investigate cell lifelines in a 15,000 L stirred tank reactor (STR) with three Elephant Ear impellers. The Stokes number of the LSPs is approx. 0.004 on a macro-scale. The vertical probability of presence, axial velocity profiles, circulation time distributions, and residence time distributions are quantified to analyze single-phase mixing heterogeneities, detect hydrodynamic compartments and conduct a Lagrangian regime analysis. Results reveal a similarly distributed probability of presence in the vertical reactor center but emphasize the LSP's sensitivity to fluctuating densities. Axial velocity distributions illustrate characteristic impeller-induced flow patterns, and circulation time distributions identify three compartments with comparatively shorter times in the axial center. Residence time distributions exhibit a similar compartmentalized profile. Moreover, the study estimates a potential oxygen deprivation zone for CHO cells in the upper compartment and demonstrates the LSP's efficacy in characterizing impeller systems. Contrary to literature, the ratio of examined global mixing times to circulation times is 1.0, highlighting macro-scale mixing. The research underscores that LSPs offer crucial insights into industrial-scale STRs, specifically for determining hydrodynamic compartments without having optical access. (2024-04-19)
Keywords: Lagrangian Sensor Particles; Circulation Time Distribution; Residence Time Distribution; Lagrangian Regime Analysis; Elephant Ear Impeller; Industrial Scale
Related publications
- DOI: 10.1016/j.cherd.2024.04.015 references this (Id 39020) publication
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Experimental Analysis of Lifelines in a 15,000 L Bioreactor by Means of …
ROBIS: 38091 has used this (Id 39020) publication of HZDR-primary research data
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Reseach data in external data repository
Publication year 2024
License: GPLv3/CCBY 4.0
Hosted on DaRUS: Link to location
DOI: 10.18419/darus-3768
Permalink: https://www.hzdr.de/publications/Publ-39020
Recent results and future perspectives with solid targets at LUNA
Ananna, C.; Barbieri, L.; Boeltzig, A.; Campostrini, M.; Casaburo, F.; Francesco Ciani, G.; Compagnucci, A.; Maria Gesuè, R.; Marsh, J.; Masha, E.; Mercogliano, D.; Rapagnani, D.; Robb, D.; Singh Sidhu, R.; Skowronski, J.
Abstract
The stellar evolution and chemical make-up of the Universe are determined by nuclear reactions occurring in a wide variety of stellar sites. Precise determinations of the cross sections of these reactions are crucial for the calculation of reaction rates and for the development of stellar evolution models. The Laboratory for Underground Nuclear Astrophysics (LUNA) collaboration has been at the forefront of the direct measurement of nuclear reactions at the low energies of astrophysical interest for the last 35 years. The many significant results achieved at LUNA have been made possible due to the low background conditions uniquely available thanks to its location deep underground at the Laboratori Nazionali del Gran Sasso. Another key aspect of these successes is due to the experience of the LUNA collaboration in the production and characterization of a variety of solid targets used in reaction measurements. In this review, the main production techniques of solid targets are described, as well as the common methods adopted for target degradation monitoring. We also present the results of recent measurements using these targets and the future plans of the LUNA collaboration for measurements using solid targets at the LUNA400 kV and the new Ion Beam Facility (IBF) 3.5 MV are also presented.
Keywords: Nuclear Astrophysics; Solid Targets; Ion Beam Accelerator; Laboratory for Underground Nuclear Astrophysics (LUNA); Gran Sasso National Laboratory
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Frontiers in Astronomy and Space Sciences 10(2024), 1325053
DOI: 10.3389/fspas.2023.1325053
Permalink: https://www.hzdr.de/publications/Publ-39019
Nuclear Physics Mid Term Plan at LNGS
Buompane, R.; Cavanna, F.; Curceanu, C.; D’Onofrio, A.; Di Leva, A.; Formicola, A.; Gialanella, L.; Gustavino, C.; Imbriani, G.; Junker, M.; Marcianò, A.; Marzaioli, F.; Nania, R.; Napolitano, F.; Piscicchia, K.; Straniero, O.; Abia, C.; Aliotta, M.; Bemmerer, D.; Best, A.; Boeltzig, A.; Bruno, C.; Caciolli, A.; Chieffi, A.; Ciani, G.; D’Agata, G.; Deboer, R. J.; de Cesare, M.; Dell’Aquila, D.; Depalo, R.; Dominguez, I.; Ferraro, F.; Garcia Duarte, J.; Guglielmetti, A.; Gyürky, G.; Hayakawa, S.; La Cognata, M.; Lamia, L.; Marcucci, L. E.; Masha, E.; Mazzocco, M.; Morales-Gallegos, E. L.; Palmerini, S.; Passariello, I.; Petraglia, A.; Piatti, D.; Pignatari, M.; Pizzone, R. G.; Porzio, G.; Rapagnani, D.; Rapisarda, G. G.; Romano, S.; Rubino, M.; Santonastaso, C.; Sergi, M. L.; Skowronski, J.; Spartà, R.; Terrasi, F.; Tumino, A.; Turkat, S.; Wiescher, M.; Zavatarelli, S.
Abstract
The Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Gran Sasso (LNGS) is one of the largest underground physics laboratory, a very peculiar environment suited for experiments in Astroparticle Physics, Nuclear Physics and Fundamental Symmetries. The newly established Bellotti Ion Beam facility represents a major advance in the possibilities of studying nuclear processes in an underground environment. A workshop was organized at LNGS in the framework of the Nuclear Physics Mid Term Plan in Italy, an initiative of the Nuclear Physics Division of the Instituto Nazionale di Fisica Nucleare to discuss the opportunities that will be possible to study in the near future by employing state-of-the-art detection systems. In this report, a detailed discussion of the outcome of the workshop is presented.
Keywords: Underground Physics; Gran Sasso National Laboratory; Astroparticle Physics; Nuclear Physics
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European Physical Journal Plus 139(2024), 224
DOI: 10.1140/epjp/s13360-023-04840-2
Permalink: https://www.hzdr.de/publications/Publ-39018
Comparison of three titanium-precursors for atomic-layer-deposited TiO2 for passivating contacts on silicon
Hiller, D.; Munnik, F.; López-Vidrier, J.; Solonenko, D.; Reif, J.; Knaut, M.; Thimm, O.; Grant, N. E.
Abstract
Atomic layer-deposited (ALD) TiO2 thin films on silicon were deposited using titanium tetrachloride (TiCl4), titanium tetraisopropoxide (TTIP), and tetrakis(dimethylamino)titanium (TDMAT) together with water vapor as the oxidant at temperatures ranging between 75 and 250 °C. The Si surface passivation quality of as-deposited and isothermally annealed samples was compared using photoconductance lifetime measurements in order to calculate their effective surface recombination velocities Seff. A low Seff of 3.9 cm/s (J0s = 24 fA/cm2) is achieved for as-deposited TiCl4-TiO2 at 75 °C when a chemically grown (i.e., from RCA cleaning) SiOx interface layer is present. Depositing TTIP-TiO2 at 200 °C on a chemically grown SiOx interface layer yields equivalent Seff values; however, in this case, TTIP-TiO2 requires a 5–15 min postdeposition forming gas anneal at 250 °C. In contrast, TDMAT-TiO2 was not found to provide a similar level of passivation with/without a chemically grown SiOx interface layer and postdeposition anneal. Modeling of the effective lifetime curves was used to determine the magnitude of the effective charge densities Qf in the TiO2 films. In all cases, Qf was found to be of the order of ∼10^11 q cm−2, meaning field-effect passivation arising from ALD TiO2 is relatively weak. By comparing the material properties of the various TiO2 films using ellipsometry, photothermal deflection spectroscopy, Raman spectroscopy, elastic recoil detection analysis, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we find experimental support for the role of Cl (in conjunction with hydrogen) playing a beneficial role in passivating dangling bond defects at the Si surface. It is concluded that low deposition temperature TiCl4 processes are advantageous, by providing the lowest Seff without any postanneal and a comparatively high growth per cycle (GPC).
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39016) publication
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Journal of Vacuum Science & Technology A 42(2024)3, 032406
DOI: 10.1116/6.0003309
Permalink: https://www.hzdr.de/publications/Publ-39016
Inkjet printing of functional materials activated by ms-range flash lamp annealing
Folgner, C.; Zhang, G.; Prucnal, S.; Rebohle, L.; Zhou, S.
Abstract
Currently, we observe a continuous need for innovative flexible optoelectronics that are present in smart homes, smart healthcare products and different sensors like gas or temperature sensors. All those applications require a fast and cheap fabrication process. In the last two decades, flash lamp annealing (FLA or photonic curing) has extended its scope of applications from traditional microelectronics to many other areas where thin film coatings are in use. The layer deposition by inkjet printing followed by FLA, preferably on flexible substrates, features a couple of advantages such as material savings, no need for lithographic structuring processes, a fast adaption to changing design requirements and easy possibility for up-scaling. In the case of nanoparticle-based inks, FLA has not only the task to evaporate remnants of the solvent, the binder and other additives, and to sinter the nanoparticles, but has advantageous in terms of energy and process time saving [1]. Currently, we are putting a roll-to-roll (R2R) tool combining inkjet printing and FLA into operation, and first successful tests to print nanoparticle inks containing transparent conductive oxides for optoelectronic applications (TCOs) like zinc oxide (ZnO), aluminum doped zinc oxide (AZO) and also metal inks like copper oxide/copper (CuO/Cu) followed by ex-situ FLA have been done.
In this poster, we will report some of these first results and discuss the corresponding application cases. In addition, the extension of the palette of available materials will address further application, as we will discuss in the case of Si, which e.g. is of high interest as anode material for LIBs and electronic devices in the area of low-cost or printed electronics.
Keywords: Inkjet printing; flash lamp annealing; roll-to-roll; nanoparticle inks; zinc oxide; metal inks; TCO; photonic curing; sensors; fabrication process
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Poster
Microprinting Materials, Methods and Applications, 18.-20.03.2024, Bad Schandau, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-39010
Investigation of the Σ Production Mechanism in p(3.5 GeV)+p Collisions
Yassine, R. A.; Arnold, O.; Becker, M.; Kämpfer, B.; Kotte, R.; Naumann, L.; HADES Collaboration
Abstract
The production of Σ hyperons in proton proton collisions at a beam kinetic energy of 3.5 GeV impinging on a liquid hydrogen target was investigated using data collected with the HADES setup. The total production cross section is found to be σ(pK+Σ) = 17.7 ± 1.7 (stat) ± 1.6 (syst) µb. Differential cross section distributions of the exclusive channel pp→ pK+Σ were analyzed in the center-of-mass, Gottfried–Jackson and helicity reference frames for the first time at the excess energy of 556 MeV. The data support the interplay between pion and kaon exchange mechanisms and clearly demonstrate the contribution of interfering nucleon resonances decaying to K +Σ . The Bonn–Gatchina partial wave analysis was employed to analyse the data. Due to the limited statistics, it was not possible to obtain an unambiguous determination of the relative contribution of intermediate nucleon resonances to the final state. However nucleon resonances with masses around 1.710 GeV / c 2 (N ∗(1710)) and 1.900 GeV / c 2 (N ∗(1900) or Δ ∗(1900)) are preferred by the fit.
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European Physical Journal A 60(2024)1, 18
DOI: 10.1140/epja/s10050-023-01214-1
Permalink: https://www.hzdr.de/publications/Publ-39009
Generation of localized, half-frequency spin waves in micron sized ferromagnetic stripes: Experiments and simulations
Copus, M. G.; Hula, T.; Heins, C.; Flacke, L.; Weiler, M.; Schultheiß, K.; Schultheiß, H.; Camley, . E.
Abstract
We demonstrate the nonlinear generation of spin-wave edge modes with half the frequency of the applied oscillating field in a Co25Fe75 ferro- magnetic stripe through micromagnetic simulations and experiments. The generation of half-frequency modes depends on the simultaneous presence of resonances near both the driving frequency and the half-frequency in different regions of the material. The half-frequency genera- tion occurs in a system that is thin enough that typical three-magnon decay would not be allowed in a ferromagnetic resonance experiment in an extended film. We find that a limited range of driving frequencies will produce a half-frequency for a given set of system parameters. This range can be tuned by the strength of the oscillating field and the strength of the static external field. Our experimental results agree well with the findings from the simulations.
Keywords: spin waves; magnons; nonlinearity; Brillouin light scattering; micromagnetic simulations
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 39007) publication
-
Applied Physics Letters 124(2024), 192401
DOI: 10.1063/5.0208756
Downloads
- Secondary publication expected from 10.04.2025
Permalink: https://www.hzdr.de/publications/Publ-39007
Radionuclide sorption in the far field: Geostatistical simulation of crystalline rock to assess uncertainties due to heterogeneities
Duckstein, A.; Pospiech, S.; Tolosana Delgado, R.; Brendler, V.
Abstract
In the event of radionuclides leaking from a deep geological repository for radioactive waste, they can reach the ecosphere through fluid migration pathways in the rock and aquifers. Retention mechanisms such as the sorption of radionuclides on the minerals along such pathways influence the migration patterns and are thus an essential part of the safety requirements. Consequently, determining the mineral composition and its spatial distribution of a crystalline host rock is an important task in the safety assessment for potential repositories.
In the SANGUR project (Systematic sensitivity analysis for mechanistic geochemical models using field data from crystalline rock) we aim to determine which parameters and their uncertainties are essential for developing models for the simulation of radionuclide retention in crystalline rock. Radionuclide retention is substantially affected by sorption processes on the mineral surfaces, described by distribution coefficients (Kd values). A subsequent sensitivity analysis will help to identify the most influential parameters.
In addition to the groundwater composition and the thermodynamic sorption data, the mineralogy and its heterogeneity of the host rock play an important role in establishing the model. For the sensitivity analysis, in turn, it is vital to be able to describe the uncertainties of the individual parameters in the model.
To quantify the uncertainties, we simulate crystalline rock based on MLA (Mineral Liberation Analyzer image) data using Multinary Random Fields geostatistics. The focus is not only on the mineral composition of the bulk rock as a function of number of mineral phases and variability in grain sizes, but above all on the determination of the mineral composition of the exposed surfaces with which the aqueous phase comes into contact and on which sorption processes will thus preferentially take place.
Besides the question of how detailed the rock must be modeled in order to adequately capture the heterogeneities, the question of the model scale or the size of the representative volume element is also addressed.
In addition to the discussion of the methodology and the results of the host rock simulations, we show the results of an initial study that enables us to determine what size the representative volume element should have in order to best describe the heterogeneities of the host rock for the subsequent calculation of the Kd values and their uncertainties.
-
Lecture (Conference)
EGU General Assembly 2024, 16.04.2024, Vienna, Austria
DOI: 10.5194/egusphere-egu24-1916
Permalink: https://www.hzdr.de/publications/Publ-39004
Investigation into the metabolic stability of 18F-labeled PSMA inhibitor derivatives bearing aryl-fluorosulfates for PET tracer development applications
Luque Consuegra, G.; Craig, A.; Kogler, J.; Ullrich, M.; Donat, C.; Kopka, K.; Stadlbauer, S.
Abstract
This poster highlights the use of the sulfur [18F]fluoride exchange approach to radiolabel a PSMA inhibitor ([18F]2) and test its radiolabeling, in vitro and in vivo properties.
- [18F]2 shows good binding kinetics compared to known radiotracers (1 nM) but ~20%
- [18F]2 binds to LNCaP xenograft sections in a similar pattern as [68Ga]Ga-PSMA-11.
- PET imaging experiments show defluorination but also accumulation in LNCaP tumor
- Further work: Radiosynthesis of [18F]4 starting from precursor 3 (in poster)
Keywords: sulfur [18F]fluoride exchange approach; Radiolabeling; PET; PSMA; Radiopharmaceuticals
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Poster
21st European Symposium on Radiopharmacy & Radiopharmaceuticals, 18.-21.04.2024, Coimbra, Portugal
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Permalink: https://www.hzdr.de/publications/Publ-39001
Hyperspectral imaging and TRI3DYN simulation study of physical sputtering from a fuzzy surface
Chang, F.; Nishijima, D.; Baldwin, M. J.; Möller, W.; Tynan, G. R.
Abstract
The influence of a fuzzy surface on the physical sputtering of Mo in He plasmas has been studied with hyperspectral imaging (HSI) measurements and simulations that couple the TRI3DYN code with an impurity transport code. The 2D profiles of the Mo I line emission intensity from HSI images reveal that the sputtering yield, Y, is reduced to ∼40 % of the smooth-surface value due to the presence of a fuzz layer, while the angular distribution of the sputtered Mo atoms might not change significantly. The simulations reproduce the Y reduction successfully, but indicate that fuzz causes an increase in the small-angle distribution of sputtered atoms. However, the increase is too small to produce an observable change in the Mo I emission profiles. A simple analytical model that assumes a single collision mean free path for a fuzz layer and considers only the primary sputtering events qualitatively reproduces the Y reduction and the small-angle distribution enhancement, explaining the geometrical effect of fuzz on physical sputtering.
Keywords: Fuzz; Hyperspectral imaging; Physical sputtering; TRI3DYN
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38996) publication
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Nuclear Materials and Energy 38(2024), 10157
DOI: 10.1016/j.nme.2023.101578
Permalink: https://www.hzdr.de/publications/Publ-38996
Study of (n,α) reactions of interest for nuclear reactors: the case of 19F(n,α)16N with SCALP detector
Chevalier, A.; Lecolley, F.-R.; Lehaut, G.; Lecouey, J.-L.; Marie, N.; Manduci, L.; Ledoux, X.; Beyer, R.; Junghans, A.; Bouland, O.; Serot, O.
Abstract
The 19F(n,α)16N cross section is of great interest for the development of the next generation IV reactors that could potentially use molten fluoride salts. Significant differences (up to a factor of 3) have been observed for this nucleus regarding the (n,α) channel. In view of improving our knowledge on this (n,α) reactions, the GrACE group (Groupe Aval du Cycle Electronucleaire) of the LPC Caen has developed a new detector named SCALP (Scintillating ionization Chamber for ALPha particle detection in neutron induced reactions). This paper deals with the first experiment carried out with this brand new detector at the new NFS facility (GANIL, Caen, France). After discussing the needs for new measurments of the 19F(n,α)16N reaction, the operating procedure of the SCALP detector will be presented, as well as the experiments that have been conducted using it. Furthermore, insights into the data acquired during our experiment, as well as the ongoing data processing and associated multi-channel analysis, will be provided.
Keywords: nELBE; (n,a); 19F(n,a)16N; Generation IV reactor; SCALP; NFS
Involved research facilities
- n-ELBE DOI: 10.58065/24017
Related publications
- DOI: 10.58065/24017 is cited by this (Id 38994) publication
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European Physical Journal Web of Conferences 294(2024), 01008
DOI: 10.1051/epjconf/202429401008
Permalink: https://www.hzdr.de/publications/Publ-38994
InvenioRDM at HZDR: Rodare
Abstract
The talk will address data publishing and the FAIR data principles by examining the central role of data policies and infrastructure services. On the path to making data findable, accessible, interoperable and reusable (FAIR), the talk will provide insights into the fundamental strategies for creating effective data policies and implementing infrastructure services that support these principles. The HZDR data publication repository RODARE will be presented as well as the underlying software Invenio, which was developed by CERN. Future developments in the context of Rodare, Zenodo and Invenio will be presented. Invenio RDM (Research Data Management) and the content of the joint project InvenioRDM will be presented as well as the first steps towards an InvenioRDM demo instance. Finally, further points such as the SciCat metadata catalogue will be discussed.
Keywords: data management; data publication; FAIR; Invenio; Rodare; InvenioRDM; Data Policy; Zenodo
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Lecture (others) (Online presentation)
MT-DMA Seminar Series 2024, 22.04.2024, online, Germany
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38992
Data publication: Ab initio path integral Monte Carlo simulations of warm dense two-component systems without fixed nodes: structural properties
Abstract
This repository contains the raw data for the publication "Ab initio path integral Monte Carlo simulations of warm dense two-component systems without fixed nodes: structural properties". All units as described in the paper / figure captions.
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-19 Open access
DOI: 10.14278/rodare.2816
Versions: 10.14278/rodare.2817
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38990
Thermochromic VO2-based coatings deposited by roll-to-roll high power impulse magnetron sputtering
Szelwicka, J.; Fahland, M.; Rezek, J.; Kaufman, M.; Munnik, F.; Vlcek, J.; von Hauff, E.
Abstract
Thermochromic vanadium dioxide (VO2) undergoes a metal-to-semiconductor (MST) transition, a property that can be exploited for energy reduction in buildings in smart windows. We present thermochromic VO2-based films prepared in a roll-to-roll process on ultra-thin glass (0.1 mm) with High Power Impulse Magnetron Sputtering (HiPIMS) without any post annealing. We characterized the film structure with X-ray diffraction, the stoichiometry by Rutherford Backscattering Spectrometry, and the optical properties with spectrophotometry. The selected films (over 2.6 m x 0.3 m), sputtered from a V-metallic tube target doped with 1.2 at.% of W (V-W target), show a transition temperature of 28 °C and 34 °C, a luminous transmittance over 50% and a modulation of the solar energy transmittance of about 7 and 10%. We monitor the deposition control parameters in the roll-to-roll process with optical emission spectroscopy, and show that both the process parameters and target history impact the thermochromic properties. Finally, we extract the charge carrier concentration and mobility by modelling the transmittance and reflectance spectra, which indicates that the VO2-coating has a slight sub-stoichiometric character.
Keywords: vanadium dioxide; thermochromic; roll-to-roll; HiPIMS; ultrathin glass
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38989) publication
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ACS Applied Energy Materials (2024)
DOI: 10.1002/ente.202400076
Permalink: https://www.hzdr.de/publications/Publ-38989
Laser-driven high-energy proton beams from cascaded acceleration regimes
Ziegler, T.; Göthel, I.; Assenbaum, S.; Bernert, C.; Brack, F.-E.; Cowan, T.; Dover, N. P.; Gaus, L.; Kluge, T.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Nishiuchi, M.; Prencipe, I.; Püschel, T.; Rehwald, M.; Reimold, M.; Schlenvoigt, H.-P.; Umlandt, M. E. P.; Vescovi Pinochet, M. A.; Schramm, U.; Zeil, K.
Abstract
Laser-driven ion accelerators can deliver high-energy, high-peak current beams and are thus attracting attention as a compact alternative to conventional accelerators. However, achieving sufficiently high energy levels suitable for applications such as radiation therapy remains a challenge for laser-driven ion accelerators. Here we generate proton beams with a spectrally separated high-energy component of up to 150 MeV by irradiating solid-density plastic foil targets with ultrashort laser pulses from a repetitive petawatt laser. The preceding laser light heats the target, leading to the onset of relativistically induced transparency upon main pulse arrival. The laser peak then penetrates the initially opaque target and triggers proton acceleration through a cascade of different mechanisms, as revealed by three-dimensional particle-in-cell simulations. The transparency of the target can be used to identify the high-performance domain, making it a suitable feedback parameter for automated laser and target optimization to enhance stability of plasma accelerators in the future.
Involved research facilities
- Draco
-
Nature Physics (2024)
DOI: 10.1038/s41567-024-02505-0
Permalink: https://www.hzdr.de/publications/Publ-38987
Role of Debye temperature in achieving large adiabatic temperature changes at cryogenic temperatures: A case study on Pr2In
Liu, W.; Scheibel, F.; Fortunato, N.; Dirba, I.; Gottschall, T.; Zhang, H.; Skokov, K.; Gutfleisch, O.
Abstract
The excellent magnetic entropy change (ΔST ) in the temperature range of 20 ∼ 77 K due to the first-order phase transition makes Pr2In an intriguing candidate for magnetocaloric hydrogen liquefaction. As an equally important magnetocaloric parameter, the adiabatic temperature change (ΔTad) of Pr2In associated with the first-order phase transition has not yet been reported. In this work, the ΔTad of Pr2In is obtained from heat capacity measurements: 2 K in fields of 2 T and 4.3 K in fields of 5 T. While demonstrating a ΔTad that is not as impressive as its remarkable ΔST, Pr2In exhibits a low Debye temperature (TD) of around 110 K. Based on these two observations, an approach that combines the mean-field and Debye models is developed to study the correlation between ΔTad, one of the most important magnetocaloric parameters, and TD, one important property of a material. The role of TD in achieving large ΔTad is revealed: materials with higher TD tend to exhibit larger ΔTad , particularly in the cryogenic temperature range. This discovery explains the absence of an outstanding ΔTad in Pr2In and can serve as a tool for designing or searching for materials with both a large ΔST and a ΔTad.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Physical Review B 109(2024), L140407
DOI: 10.1103/PhysRevB.109.L140407
arXiv: arXiv:2311.05022
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38986
Electrical characterization of multi-gated WSe2/MoS2 van der Waals heterojunctions
Chava, P.; Kateel, V.; Watanabe, K.; Tanihushi, T.; Helm, M.; Mikolajick, T.; Erbe, A.
Abstract
Transistor measurements
Keywords: 2D-materials; heterostructures; transistors
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38985) publication
-
Electrical characterization of multi‑gated WSe2/MoS2 van der Waals …
ROBIS: 38872 has used this (Id 38985) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-17 Restricted access
DOI: 10.14278/rodare.2812
Versions: 10.14278/rodare.2813
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38985
Künstliche Intelligenz im Alltag
Abstract
Künstliche Intelligenz ist längst nicht mehr nur ein Zukunftsthema, sondern prägt unseren Alltag in vielfältiger Weise. Sie erstellt ganze Kochmagazine, formt den Musikgeschmack und hilft beim Schreiben von Kurznachrichten: Die Künstliche Intelligenz (KI/AI) ist in unserem Alltag angekommen.
In unserem Vortrag entführen wir Sie in die Welt der Künstlichen Intelligenz: Von den Ursprüngen und Schlüsselmomenten ihrer Entwicklung, über alltägliche Anwendungen bis hin zu spezialisierten Einsatzgebieten wie in der Medizin. Wir beleuchten, wie KI unseren Alltag bereichert und gleichzeitig Herausforderungen aufwirft, und enden mit einem Ausblick auf die zukünftige Rolle der KI in Gesellschaft und Technologie. Ein kompakter, aber tiefgehender Einblick in das faszinierende Feld der KI erwartet Sie.
Keywords: Künstliche Intelligenz; Wissenschaftskommunikation
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Lecture (others)
Info-Veranstaltung Künstliche Intelligenz, 18.04.2024, Löbau, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38984
Software publication: 3D detection and tracking of deformable bubbles in swarms with the aid of deep learning models
Hessenkemper, H.; Wang, L.; Lucas, D.; Shiyong, T.; Rui, N.; Ma, T.
Abstract
Software for 3D tracking of deformable bubbles in swarms
Keywords: 3D Lagrangian bubble tracking; Bubble swarms; Deformable bubbles; Deep learning
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Software in the HZDR data repository RODARE
Publication date: 2024-04-17 Open access
DOI: 10.14278/rodare.2810
Versions: 10.14278/rodare.2811
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38982
Data publication: 3D detection and tracking of deformable bubbles in swarms with the aid of deep learning models
Hessenkemper, H.; Wang, L.; Lucas, D.; Shiyong, T.; Rui, N.; Ma, T.
Abstract
Synthetic data set for 3D tracking of bubbles in multi-view measurements.
Keywords: 3D Lagrangian bubble tracking; Bubble swarms; Deformable bubbles; Deep learning
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-17 Open access
DOI: 10.14278/rodare.2808
Versions: 10.14278/rodare.2809
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38981
Liquid crystal wave plate operating close to 18 THz
Novelli, F.; Friebel, P.; Murillo-Sanchez, M. L.; Klopf, J. M.; Cattaneo, L.
Abstract
Controlling the properties of mid- and far-infrared radiation can provide a means to transiently alter the properties of materials for novel applications. However, a limited number of optical elements are available to control its polarization state. Here we show that a 15-µm thick liquid crystal cell containing 8CB (4-octyl-4′-cyanobiphenyl) in the ordered, smectic A phase can be used as a phase retarder or wave plate. This was tested using the bright, short-pulsed (∼1 ps) radiation centered at 16.5 µm (18.15 THz) that is emitted by a free electron laser at high repetition rate (13 MHz). These results demonstrate a possible tool for the exploration of the mid- and far-infrared range and could be used to develop novel metamaterials or extend multidimensional spectroscopy to this portion of the electromagnetic spectrum.
Keywords: FEL; THz; polarization; birefringence; MIR
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- F-ELBE
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 38976) publication
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Optics Letters 49(2024), 2061
DOI: 10.1364/OL.519177
Downloads
- Secondary publication expected from 10.04.2025
Permalink: https://www.hzdr.de/publications/Publ-38976
Synthese, Stabilitätsbestimmung und Radiomarkierung neuer Pym-Azamakrozyklen mit Barium-131, Actinium-225, Lanthan-133, und Blei-212
Blei, M. K.; Drobot, B.; Stadlbauer, S.; Kopka, K.; Kretzschmar, J.; Mamat, C.
Abstract
Die Radiumisotope Ra-223/-224 mit ihrem diagnostischen Gammastrahler Ba-131 (SPECT) sind ideale Kandidaten für die zielgerichtete Alphatherapie. Um Ra2+ in Radiokonjugaten zu nutzen, muss dieses jedoch stabil gebunden werden. Der Chelator Macropa (mcp) bildet nach bisherigen Erkenntnissen die stabilsten Komplexe, jedoch sind diese für In-vivo-Anwendungen nicht stabil genug. Daher wurden neuartige makrozyklische Chelatoren auf Basis von macropa entwickelt und zusätzlich eine Anwendung für La, Ac und Pb in Betracht gezogen.
Keywords: macropa; Actinium-225; theranostisches Konzept; Barium-131
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Lecture (Conference)
DGN Jahrestagung, 10.-13.04.2024, Leipzig, Deutschland -
Abstract in refereed journal
Nuklearmedizin 63(2024), 91
DOI: 10.1055/s-0044-1782286
Permalink: https://www.hzdr.de/publications/Publ-38974
Iod-123-basierte Radiohybridkonjugate als diagnostisches Match zur zielgerichteten Alphatherapie mit Actinium-225
Krönke, T.; Zarschler, K.; Reissig, F.; Kopka, K.; Stadlbauer, S.; Mamat, C.
Abstract
Macropa-PSMA-Konjugate, die zur zielgerichteten Alphatherapie mit Ac-225 dienen, werden mit einem Albuminbinder verknüpft. Neben der Verbesserung des pharmakologischen Verhaltens in vivo bietet die albuminbindende Einheit die Grundlage eines theranostischen Ansatzes. Neben der Komplexierung des Alphaemitters Ac-225 wird zusätzlich die Einführung des SPECT-Nuklids I-123 im gleichen Molekül ermöglicht. Vorteilhaft sind die milden Bedingungen der Radioiodierung sowie eine Halbwertszeit (t1/2 = 13,2 h), welche die Bildgebung länger zirkulierender Substanzen ermöglicht.
Keywords: macropa; Actinium-225; theranostisches Konzept
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Lecture (Conference)
DGN Jahrestagung, 10.-13.04.2024, Leipzig, Deutschland -
Abstract in refereed journal
Nuklearmedizin 63(2024), 111
DOI: 10.1055/s-0044-1782344
Permalink: https://www.hzdr.de/publications/Publ-38973
Data publication: Revisiting Metal−Organic Frameworks Porosimetry by Positron Annihilation: Metal Ion States and Positronium Parameters
Attallah, A. G.; Bon, V.; Maity, K.; Zaleski, R.; Hirschmann, E.; Kaskel, S.; Wagner, A.
Abstract
This dataset includes the positron data.
Keywords: Metal-Organic Frameworks (MOFs); Positron Annihilation Lifetime Spectroscopy (PALS); Positronium quenching; Paramagnetic Effects; MOF Pore Analysis
Related publications
- DOI: 10.1021/acs.jpclett.4c00762 references this (Id 38971) publication
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Revisiting Metal−Organic Frameworks Porosimetry by Positron Annihilation …
ROBIS: 38970 has used this (Id 38971) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-15 Open access
DOI: 10.14278/rodare.2804
Versions: 10.14278/rodare.2805
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38971
Revisiting Metal−Organic Frameworks Porosimetry by Positron Annihilation: Metal Ion States and Positronium Parameters
Attallah, A. G.; Bon, V.; Maity, K.; Zaleski, R.; Hirschmann, E.; Kaskel, S.; Wagner, A.
Abstract
Metal-organic frameworks (MOFs) stand as pivotal porous materials with exceptional surface areas, adaptability, and versatility. Positron Annihilation Lifetime Spectroscopy (PALS) is an indispensable tool for characterizing MOF porosity, especially micro- and mesopores in both open and closed states. Notably, PALS offers porosity insights independently of probe molecules, vital for detailed characterization without structural transformations. This study explores how metal ion states in MOFs affect PALS results. We find significant differences in measured porosity due to paramagnetic or oxidized metal ions compared to simulated values. By analyzing CPO-27(M) (M=Mg, Co, Ni), with identical pore dimensions, we observe distinct PALS data alterations based on metal ions. Paramagnetic Co and Ni ions hinder and quench positroni-um (Ps) formation, resulting in smaller measured pore volumes and sizes. Mg only quenches Ps, leading to underestimated pore sizes without volume distortion. This underscores metal ions' pivotal role in PALS outcomes, urging caution in interpreting MOF porosity.
Keywords: Metal-Organic Frameworks (MOFs); Positron Annihilation Lifetime Spectroscopy (PALS); Positronium quenching; Paramagnetic Effects; MOF Pore Analysis
Related publications
-
Data publication: Revisiting Metal−Organic Frameworks Porosimetry by Positron …
ROBIS: 38971 HZDR-primary research data are used by this (Id 38970) publication
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The Journal of Physical Chemistry Letters 15(2024), 4560-4567
DOI: 10.1021/acs.jpclett.4c00762
Permalink: https://www.hzdr.de/publications/Publ-38970
Growth of Perpendicular Magnetic Anisotropy in Gallium-substituted Yttrium Iron Garnet Thin Films
Lenz, K.; Gladii, O.; Pablo-Navarro, J.; Oelschlägel, A.; Heller, R.; Lindner, J.; Surzhenko, O.; Dubs, C.
Abstract
We investigate the effect of Ga substitution on the magnetic properties of nanometer-thin Ga:YIG (Y_3Fe_5-xGa_xO_12) films grown by liquid phase epitaxy (LPE) [1,2]. The Ga content was varied between 1.1–1.3 f.u. and film thicknesses were 30 to 230 nm. The substitution of Fe sites by Ga ions reduces the remanent magnetization. Together with the tensile strain it causes a stronger out-of-plane uniaxial anisotropy (PMA) making thin Ga:YIG films perpendicularly magnetized. We also demonstrate that, independent of the thickness and of the substrate orientation, i.e. GGG(111) vs. (001), the PMA gradually increases with the Ga-content, resulting in a 14 times larger perpendicular anisotropy for the highest Ga content used in this study compared to pure YIG. This allows for an easy tuning of the PMA by variation of the Ga concentration. One feature of YIG almost remains: the Gilbertdamping increases only slightly with the amount of Ga. The inhomogeneous broadening shows a stronger dependence.
Keywords: ferromagnetic resonance; garnets; perpendicular magnetic anisotropy; damping; magnetization dynamics
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Poster
DPG Frühjahrstagung der SKM 2024, 17.-22.03.2024, Berlin, Deutschland -
Poster
Magnonics 2023, 30.07.-03.08.2023, Le Touquet - Paris-Plage, Frankreich
Permalink: https://www.hzdr.de/publications/Publ-38967
Magnetization Dynamics in Nanostructures probed by Ferromagnetic Resonance
Abstract
Magnetization Dynamics in Nanostructures probed by Ferromagnetic Resonance
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38966) publication
-
Invited lecture (Conferences)
Dynamics in Magnetic Systems 2024 - DIMS, 08.-11.04.2024, Ostrov/Tisá, Tschechien
Permalink: https://www.hzdr.de/publications/Publ-38966
Breaking the Vicious Cycle of Warm Dense Matter Diagnostics: From X-ray Scattering to Ab-initio Simulations
Abstract
Matter at extreme densities and temperatures displays a complex quantum behavior that is characterized by
Coulomb interactions, thermal excitations, and partial ionization. Such warm dense matter (WDM) is
ubiquitous throughout the universe and occurs in a host of astrophysical objects such as giant planet
interiors and white dwarf atmospheres. A particularly intriguing application is given by inertial confinement
fusion, where both the fuel capsule and the ablator have to traverse the WDM regime in a controlled way to
reach ignition. In practice, rigorously understanding WDM is highly challenging both from experimental
measurements and numerical simulations [1]. On the one hand, interpreting and diagnosing experiments with
WDM requires a suitable theoretical description. One the other hand, there is no single method that is
capable of accurately describing the full range of relevant densities and temperatures, and the interpretation
of experiments is, therefore, usually based on a number of de-facto uncontrolled approximations. The result
is the vicious cycle of WDM diagnostics: making sense of experimental observations requires theoretical
modeling, whereas theoretical models must be benchmarked against experiments to verify their inherent
assumptions. In this work, we outline a strategy to break this vicious cycle by combining the X-ray Thomson
scattering (XRTS) technique [2] with new ab initio path integral Monte Carlo (PIMC) capabilities [3,4,5]. As
a first step, we have proposed to interpret XRTS experiments in the imaginary-time (Laplace) domain, which
allows for the model-free diagnostics of the temperature [6] and normalization [7]. Moreover, by switching
to the imaginary-time, we can directly compare our quasi-exact PIMC calculations with the experimental
measurement [5]. This opens up novel ways to diagnose the experimental conditions, as we have recently
demonstrated for the case of strongly compressed beryllium at the National Ignition Facility. Our results
open up new possibilities for improved XRTS set-ups that are specifically designed to be sensitive to
particular parameters of interest [8]. Moreover, the presented PIMC capabilities are important in their own
right and will allow for a gamut of applications, including equation-of-state calculations and the
estimation of structural properties and linear response functions.
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Lecture (others)
Theorieseminar Physik Uni Kiel, 11.04.2024, Kiel, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38965
Detector Development for a Double-Differential Cross Section Experiment with the Emission of Light Charged Particles from High Energy Neutrons
Dietz, M.; Beyer, R.; Junghans, A.; Nolte, R.; Pirovano, E.; Romanets, Y.; Vaz, P.; n_TOF Collaboration
Abstract
Double-differential cross section (DDX) data on the neutron-induced emission of light charged particles are required for assessing the risk of secondary tumors in particle radiation therapy. There are only very few DDX data available for discrete neutron energies close to and above 100 MeV for carbon. A measurement of DDX on carbon is planned at continuous neutron energies from 20 MeV to 200 MeV with particle detector telescopes at n_TOF (CERN). Several detector development criteria and challenges are reported such as coincidence timing and electromagnetic oscillations for high neutron energy events with particle separation.
Keywords: CERN n_ToF; Double-Differential Cross Section; Carbon; Time-of-Flight; High Neutron Energy; Particle Detector Telescope; Neutron Dosimetry
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European Physical Journal Web of Conferences 288(2023), 01003
DOI: 10.1051/epjconf/202328801003
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Permalink: https://www.hzdr.de/publications/Publ-38963
Rieger, Schwabe, Suess-de Vries: The sunny beats of resonance
Stefani, F.; Horstmann, G. M.; Klevs, M.; Mamatsashvili, G.; Weier, T.
Abstract
We propose a self-consistent explanation of Rieger-type periodicities, the Schwabe cycle, and the Suess-de Vries cycle of the solar dynamo in terms of resonances of various wave phenomena with gravitational forces exerted by the orbiting planets. Starting on the high-frequency side, we show that the two-planet spring tides of Venus, Earth, and Jupiter are able to excite magneto-Rossby waves, which can be linked with typical Rieger-type periods. We argue then that the 11.07-year beat period of those magneto-Rossby waves synchronizes an underlying conventional alpha-Omega dynamo by periodically changing either the field storage capacity in the tachocline or some portion of the alpha-effect therein. We also strengthen the argument that the Suess-de Vries cycle appears as an 193-year beat period between the 22.14-year Hale cycle and a spin-orbit coupling effect related with the 19.86-year rosette-like motion of the Sun around the barycenter.
Involved research facilities
- DRESDYN
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Solar Physics 299(2024), 51
DOI: 10.1007/s11207-024-02295-x
Permalink: https://www.hzdr.de/publications/Publ-38962
Enhanced ion acceleration from transparency-driven foils demonstrated at two ultraintense laser facilities
Dover, N. P.; Ziegler, T.; Assenbaum, S.; Bernert, C.; Bock, S.; Brack, F.-E.; Cowan, T.; Ditter, E. J.; Garten, M.; Gaus, L.; Göthel, I.; Hicks, G. S.; Kiriyama, H.; Kluge, T.; Koga, J. K.; Kon, A.; Kondo, K.; Kraft, S.; Kroll, F.; Lowe, H. F.; Metzkes-Ng, J.; Miyatake, T.; Najmudin, Z.; Püschel, T.; Rehwald, M.; Reimold, M.; Sakaki, H.; Schlenvoigt, H.-P.; Shiokawa, K.; Umlandt, M. E. P.; Schramm, U.; Zeil, K.; Nishiuchi, M.
Abstract
Laser-driven ion sources are a rapidly developing technology producing high energy, high peak current beams. Their suitability for applications, such as compact medical accelerators, motivates development of robust acceleration schemes using widely available repetitive ultraintense femtosecond lasers. These applications not only require high beam energy, but also place demanding requirements on the source stability and controllability. This can be seriously affected by the laser temporal contrast, precluding the replication of ion acceleration performance on independent laser systems with otherwise similar parameters. Here, we present the experimental generation of >60 MeV protons and >30 MeV u^{−1} carbon ions from sub-micrometre thickness Formvar foils irradiated with laser intensities >10^{21} W/cm^{2}. Ions are accelerated by an extreme localised space charge field ≳30 TVm^{−1}, over a million times higher than used in conventional accelerators. The field is formed by a rapid expulsion of electrons from the target bulk due to relativistically induced transparency, in which relativistic corrections to the refractive index enables laser transmission through normally opaque plasma. We replicate the mechanism on two different laser facilities and show that the optimum target thickness decreases with improved laser contrast due to reduced pre-expansion. Our demonstration that energetic ions can be accelerated by this mechanism at different contrast levels relaxes laser requirements and indicates interaction parameters for realising application-specific beam delivery.
Involved research facilities
- Draco
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Light: Science and Applications 12(2023), 71
DOI: 10.1038/s41377-023-01083-9
Cited 10 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-38955
Data publication: Coherent phonon and unconventional carriers in the magnetic kagome metal Fe3Sn2
Goncalves Faria, M. V.; Pashkin, O.; Winnerl, S.; Helm, M.; Uykur, E.
Abstract
This data set presents the optical pump-probe traces of Fe3Sn2 as function of temperature and excitation fluence. It also shows initial data analysis with exponential fits, relaxation times and FFT calculations.
Related publications
- DOI: 10.1038/s41535-024-00642-6 references this (Id 38950) publication
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Coherent phonon and unconventional carriers in the magnetic kagome metal Fe3Sn2
ROBIS: 37706 has used this (Id 38950) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-10 Open access
DOI: 10.14278/rodare.2796
Versions: 10.14278/rodare.2797
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38950
Magnetic Properties of Non-van der Waals 2D Materials
Barnowsky, T.; Ghorbani-Asl, M.; Heine, T.; Curtarolo, S.; Krasheninnikov, A. V.; Friedrich, R.
Abstract
While 2D materials are traditionally derived from bulk layered crystals
bonded by weak van der Waals (vdW) forces, the recent surprising
experimental realization of non-vdW 2D compounds obtained from
non-layered transition metal oxides [1] foreshadows a new direction in
2D systems research.
As outlined by our recent data-driven investigations [2, 3], these
materials exhibit unique magnetic properties owing to the magnetic
cations at the surface of the sheets. Despite of several ferromagnetic
candidates, even for the antiferromagnetic representatives, the surface
spin polarizations are diverse ranging from moderate to large values
modulated in addition by ferromagnetic and antiferromagnetic in-plane
coupling. At the same time, chemical tuning by surface passivation
provides a valuable handle to further control the magnetic properties
of these novel 2D compounds [4] thus rendering them an attractive
platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[3] T. Barnowsky et al., Adv. Electron. Mater. 9, 2201112 (2023).
[4] T. Barnowsky et al., submitted, arXiv:2310.07329 (2023).
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38948) publication
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Lecture (Conference)
Frühjahrestagung der Deutschen Physikalischen Gesellschaft, 20.03.2024, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38948
Efficient Modelling and Synthesizability Descriptors of High-Entropy Ceramics
Friedrich, R.; Divilov, S.; Eckert, H.; Hicks, D.; Oses, C.; Toher, C.; Curtarolo, S.
Abstract
High entropy materials have recently attracted significant interest due to their appealing mechanical, catalytic, and electronic properties.
High-entropy ceramics consist of an ordered anion sublattice of carbon, nitrogen or oxygen and a disordered cation sublattice maximizing configurational entropy by randomly occupying it by five or more cation species (transition metal elements).
The reliable computational modelling of such systems can be realized by the partial occupation algorithm [1] implemented within the AFLOW software for materials design [2,3] by expanding the disordered system into a large set of ordered structures. These cells can then be treated by high-throughput ab initio calculations. For the actual realization of high-entropy materials, predictive synthesizability descriptors such as the entropy-forming ability (EFA) [4] are needed. We present here results on several high-entropy ceramic candidates, apply different synthesizability descriptors, and study their electronic and mechanical properties.
[1] K. Yang et al., Chem. Mater. 28, 6484 (2016).
[2] C. Oses et al., Comput. Mater. Sci. 217, 111889 (2023).
[3] M. Esters et al., Comput. Mater. Sci. 216, 111808 (2023).
[4] P. Sarker et al., Nat. Commun. 9, 4980 (2018).
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38947) publication
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Poster
Frühjahrestagung der Deutschen Physikalischen Gesellschaft, 19.03.2024, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38947
Data Science for Physicists Tutorial: Introduction to Deep Learning with a focus on Convolutional Neural Networks
Abstract
Data Science is playing an ever increasing role in physics. While some departments have offered courses, many of the examples are in the context of social science and other disciplines. In this tutorial, we will introduce data science in the physics context. We will start by introducing Jupyter notebooks and how to explore and visualize data. We will then introduce unsupervised learning techniques including clustering, random forests, etc. We will conclude with an introduction to neural networks and object tracking.
Graduate students, post-docs, and other scientists interested in learning how to apply data science to their research should attend this tutorial. The lectures will provide an introduction to data science and its applications in physics. We assume that participants will have some experience with Python, Numpy, and Matplotlib at the level of a software carpentry course and we will provide a link to learning materials before the tutorial.
Topics covered:
Data visualization and exploratory data analysis
Unsupervised learning
Convolutional neural networks
Keywords: Tutorial; Machine Learning; Deep Learning; Data Science
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Invited lecture (Conferences)
March Meeting 2024, 03.-08.03.2024, Minneapolis, Minnesota, USA
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Permalink: https://www.hzdr.de/publications/Publ-38943
Analysis scripts for processing the 2806 experiment at European XFEL
Abstract
The set of scripts used to analyse experimental data of the 2806 proposal at the European XFEL. The data and experiment are described in the respective paper, link to which will be added here later.
The analysis goes in three big steps, corresponding to the 3 folder:
1) analysis performed on the maxwell server of desy - this steps process the image data and export raw spectra into pickle files
2) offline processing - the pickle files are calibrated, and some fine tuning and decomposition is performed to produce clean usable x-ray spectra.
3) The result of step (2) is used to fit and identify the resonances and ohter atomic processes.
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Software in the HZDR data repository RODARE
Publication date: 2024-04-04 Open access
DOI: 10.14278/rodare.2790
Versions: 10.14278/rodare.2791
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-38939
Operando double-edge high-resolution X-ray absorption spectroscopy study of BiVO4 photoanodes
Piccioni, A.; Kesavan, J. K.; Amidani, L.; Mazzaro, R.; Berardi, S.; Caramori, S.; Pasquini, L.; Boscherini, F.
Abstract
High energy resolution fluorescence detected X-ray absorption spectroscopy is a powerful method for probing the electronic structure of functional materials. The X-ray penetration depth and photon-in/photon-out nature of the method allow operando experiments to be performed, in particular in electrochemical cells. Here, operando high-resolution X-ray absorption measurements of a BiVO4 photoanode are reported, simultaneously probing the local electronic states of both cations. Small but significant variations of the spectral lineshapes induced by the applied potential were observed and an explanation in terms of the occupation of electronic states at or near the band edges is proposed.
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Journal of Synchrotron Radiation 31(2024)3
DOI: 10.1107/S1600577524002741
Permalink: https://www.hzdr.de/publications/Publ-38938
Spectra from 2806 experiment at European XFEL
Abstract
Experimental spectra from European XFEL proposal n. 2806, described in following publication. Link to publication will be added here once published.
The Cu_3um.pickle file contains the processed experimental spectra for various xfel photon energies and irradiatied energy density. The file show_data.py is a python script which is showing how the data file can be read and the spectra plotted and interpreted.
Resonances.xls is a table with identified resonances from the spectra, it is a copy of Table II in the manuscript.
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-04 Open access
DOI: 10.14278/rodare.2788
Versions: 10.14278/rodare.2789
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-38937
Tunable room-temperature nonlinear Hall effect from surfaces of elementary bismuth thin films
Abstract
In the past years, there is an active research of materials displaying the non-linear Hall effect with time-reversal symmetry [1-5]. From a fundamental point of view, this quantum transport effect provides a direct way to detect in nonmagnetic materials the Berry curvature – a quantity in which the geometry of the electronic wavefunctions is encoded. The nonlinear Hall effect is also at the basis of terahertz optoelectronic applications of interest for instance for sixth generation (6G) communication networks.
An appropriate material platform for such applications should satisfy a number of criteria: i) the nonlinear Hall effect should survive up to room temperature; ii) the effect should be tunable; iii) the material fabrication should be technologically relevant (simple chemical composition of the material and low-cost microstructure); iv) ideally the material should not contain toxic heavy rare-earth elements. So far, candidate materials address only partially these requirements.
Here, we discover the first material addressing all the requirements at the same time: polycrystalline bismuth thin films [6]. We demonstrate that in this elemental green (semi)metal, the room-temperature nonlinear Hall effect is generated by surface states that are characterized by a Berry curvature triple: a quantity governing a skew scattering effect that generates non-linear transverse currents. Furthermore, we also show that the strength of nonlinear Hall effect can be controlled on demand using an extrinsic classical shape effect: the geometric nonlinear Hall effect. We demonstrate this by fabricating arc-shaped bismuth Hall bars. This endows the nonlinear Hall effect of Bismuth with the tunability encountered only in low-dimensional materials at low temperatures.
To show the potential of polycrystalline Bi thin films for optoelectronic applications in the terahertz (THz) spectral domain, we have performed high harmonic generation experiments. Polycrystalline Bi thin films reveal a high efficiency of THz third-harmonic generation (THG) that reaches levels >1% at room temperature. Moreover, our material possesses a non-saturating trend of the efficiency of the THz THG. This enables the use of Bi thin films for high- and wide- THz bandwidth electronics which works at high peak power and long pulses.
[1] Z. Z. Du et al., Nonlinear Hall effects. Nature Reviews Physics 3, 744 (2021).
[2] I. Sodemann et al., Quantum Nonlinear Hall Effect Induced by Berry Curvature Dipole in Time-Reversal Invariant Materials. Phys. Rev. Lett. 115, 216806 (2015).
[3] Q. Ma et al., Observation of the nonlinear Hall effect under time-reversal-symmetric conditions. Nature 565, 337 (2019).
[4] K. Kang et al., Nonlinear anomalous Hall effect in few-layer WTe2. Nature Mater. 18, 324 (2019).
[5] P. He et al., Quantum frequency doubling in the topological insulator Bi2Se3. Nature Communications 12, 698 (2021).
[6] P. Makushko et al., A tunable room-temperature nonlinear Hall effect in elemental bismuth thin films. Nature Electronics 7, 207 (2024).
Keywords: nonlinear Hall effect; Bi thin films
Involved research facilities
- Radiation Source ELBE DOI: 10.17815/jlsrf-2-58
- High Magnetic Field Laboratory (HLD)
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
- T-ELBE
Related publications
- DOI: 10.17815/jlsrf-2-58 is cited by this (Id 38933) publication
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38933) publication
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Invited lecture (Conferences)
(Online presentation)
KUJI QMAT Seminar of the collaboration network including 4 countries (Korea, United Kingdom, Japan, Italy) on the oxide superconducting-spintronics project, 16.05.2024, online, online
Permalink: https://www.hzdr.de/publications/Publ-38933
Data Publication: Positron emission tomography quantifies crystal surface reactivity during sorption reactions
Schöngart, J.; Kulenkampff, J.; Fischer, C.
Abstract
This dataset contains time resolved positron emission tomography (pet) images of a transport study in artificial sediment, as well as ct images of the used sample.
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-03 Closed access
DOI: 10.14278/rodare.2785
Versions: 10.14278/rodare.2786
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Permalink: https://www.hzdr.de/publications/Publ-38931
Data publication: Separated electronic and strain interfaces in core/dual-shell nanowires: unlocking the potential of strained GaAs for applications across near-infrared
Sun, X.; Pashkin, O.; Moebus, F.; Hübner, R.; Winnerl, S.; Helm, M.; Dimakis, E.
Abstract
This dataset is raw streak camera images for nanowire, PL spectra, python code for fitting.
Keywords: nanotechnology; semiconductors; strain engineering; heterostructures; charge carrier dynamics
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-04-03 Restricted access
DOI: 10.14278/rodare.2783
Versions: 10.14278/rodare.2784
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38930
Collective out-of-plane magnetization reversal in tilted stripe domain systems via a single point of irreversibility
Heinig, P.; Salikhov, R.; Samad, F.; Fallarino, L.; Patel, G. I.; Kakay, A.; Kiselev, N. S.; Hellwig, O.
Abstract
Periodic magnetic stripe domain patterns are a prominent feature of perpendicular anisotropy thin film systems. Here, we focus on the behavior of [Co(3.0 nm)/Pt(0.6 nm)]\textsubscript{$X$} multilayers within the transitional regime from preferred in-plane (IP), $X=6$, to out-of-plane (OOP), $X=22$, magnetization orientation, particularly, we examine a sample with $X=11$ repetitions, which exhibits a remanent state characterized by a significant presence of both OOP and IP magnetization components, here referred to as the "tilted" stripe domain state*. We investigate this specific sample with vibrating sample magnetometry, magnetic force microscopy and micromagnetic simulations, and find an unusual OOP field reversal behavior via a remanent parallel stripe domain state and a single point of irreversibility. Finally, we show that this characteristic reversal behavior is a rather general feature of transitional IP to OOP systems by comparing the Co/Pt multilayers with c-axis single Co thin films and Fe/Gd multilayers. \newline *[L. Fallarino et al., Phys. Rev. B 99, 024431 (2019)]
Keywords: tilted magnetization; single point of irreversibility; Co/Pt multilayer
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
- Data Center
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38928) publication
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Poster
87. Jahrestagung der DPG und DPG-Frühjahrstagung, 17.-22.03.2024, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38928
Understanding the collective out-of-plane magnetization reversal in tilted stripe domain systems via a single point of irreversibility
Heinig, P.; Salikhov, R.; Samad, F.; Fallarino, L.; Patel, G. I.; Kakay, A.; Kiselev, N. S.; Hellwig, O.
Abstract
Perpendicular anisotropy thin film systems are well known for their periodic magnetic stripe domain structures. In this study, we focus on investigating the behavior of [Co(3.0 nm)/Pt(0.6 nm)]\textsubscript{$X$} multilayers within the transitional regime from preferred in-plane (IP) to out-of-plane (OOP) magnetization orientation, particularly, we examine the sample with $X=11$ repetitions, which exhibits a remanent state characterized by a significant presence of both OOP and IP magnetization components, here referred to as the "tilted" stripe domain state*. Using vibrating sample magnetometry, magnetic force microscopy and micromagnetic simulations we investigate this specific sample and find an unusual OOP field reversal behavior via a remanent parallel stripe domain state and a single point of irreversibility. While the reversal via distinct points of irreversibility is qualitatively similar to that of a nano-sized Stoner Wohlfarth particle or a vortex reversal in a micron-sized IP magnetized disk, our system is macroscopic. Finally, we show that this characteristic behavior is a rather general feature of transitional IP to OOP systems. \newline *[L. Fallarino et al., Phys. Rev. B 99, 024431 (2019)]
Keywords: tilted magnetization; single point of irreversibility; Co/Pt multilayer
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
- Data Center
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38927) publication
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Lecture (Conference)
87. Jahrestagung der DPG und DPG-Frühjahrstagung, 17.-22.03.2024, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38927
Evidence of free-bound transitions in warm dense matter
Dornheim, T.; Böhme, M.; Kraus, D.; Preston, T.; Döppner, T.; Moldabekov, Z.; Baczewski, A.; Fletcher, L.; Vorberger, J.
Abstract
Warm dense matter (WDM) is now routinely created and probed in laboratories
around the world, providing unprecedented insights into conditions achieved in
stellar atmospheres, planetary interiors, and inertial confinement fusion
experiments. However, the interpretation of these experiments is often filtered
through models with systematic errors that are difficult to quantify. Due to the
simultaneous presence of quantum degeneracy and thermal excitation, processes in
which free electrons are de-excited into thermally unoccupied bound states
transferring momentum and energy to a scattered x-ray photon become viable [1].
Here we show that such free-bound transitions are a particular feature of WDM and
vanish in the limits of cold and hot temperatures. The inclusion of these processes
into the analysis of recent X-ray Thomson Scattering (XRTS) experiments on
WDM at the National Ignition Facility [2] (see the figure below) and the Linac
Coherent Light Source [3] significantly improves model fits, indicating that free-
bound transitions have been observed without previously being identified. This
interpretation is corroborated by agreement with a recently developed model-free
thermometry technique [4,5] and presents an important step for precisely
characterizing and understanding the complex WDM state of matter.
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Poster
Current challenges in the physics of white dwarf stars, 25.-29.03.2024, Santa Fe, USA
Permalink: https://www.hzdr.de/publications/Publ-38925
Breaking the vicious cycle of warm dense matter diagnostics
Abstract
Matter at extreme densities and temperatures displays a complex quantum behavior that is characterized by Coulomb interactions, thermal excitations, and partial ionization. Such warm dense matter (WDM) is ubiquitous throughout the universe and occurs in a host of astrophysical objects such as giant planet interiors and white dwarf atmospheres. A particularly intriguing application is given by inertial confinement fusion, where both the fuel capsule and the ablator have to traverse the WDM regime in a controlled way to reach ignition.
In practice, rigorously understanding WDM is highly challenging both from experimental measurements and numerical simulations [1]. On the one hand, interpreting and diagnosing experiments with WDM requires a suitable theoretical description. One the other hand, there is no single method that is capable of accurately describing the full range of relevant densities and temperatures, and the interpretation of experiments is, therefore, usually based on a number of de-facto uncontrolled approximations. The result is the vicious cycle of WDM diagnostics: making sense of experimental observations requires theoretical modeling, whereas theoretical models must be benchmarked against experiments to verify their inherent assumptions.
In this work, we outline a strategy to break this vicious cycle by combining the X-ray Thomson scattering (XRTS) technique [2] with new ab initio path integral Monte Carlo (PIMC) capabilities [3,4,5]. As a first step, we have proposed to interpret XRTS experiments in the imaginary-time (Laplace) domain, which allows for the model-free diagnostics of the temperature [6] and normalization [7]. Moreover, by switching to the imaginary-time, we can directly compare our quasi-exact PIMC calculations with the experimental measurement [5]. This opens up novel ways to diagnose the experimental conditions, as we have recently demonstrated for the case of strongly compressed beryllium at the National Ignition Facility.
Our results open up new possibilities for improved XRTS set-ups that are specifically designed to be sensitive to particular parameters of interest [8]. Moreover, the presented PIMC capabilities are important in their own right and will allow for a gamut of applications, including equation-of-state calculations and the estimation of structural properties and linear response functions.
[1] T. Dornheim et al., Phys. Plasmas 30, 032705 (2023)
[2] S. Glenzer and R. Redmer, Rev. Mod. Phys. 81, 1625 (2009)
[3] T. Dornheim et al., J. Phys. Chem. Lett. 15, 1305-1313 (2024)
[4] T. Dornheim et al., arXiv:2403.01979
[5] T. Dornheim et al., arXiv:2402.19113
[6] T. Dornheim et al., Nature Commun. 13, 7911 (2022)
[7] T. Dornheim et al., arXiv:2305.15305
[8] Th. Gawne et al., arXiv:2403.02776
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Lecture (others)
Theory Seminar at Sandia National Laboratory, 20.03.2024, Albuquerque, USA
Permalink: https://www.hzdr.de/publications/Publ-38924
Rückhaltung von Uran durch einen gekoppelten mikrobiellen Sorptions-Reduktionsmechanismus
Hilpmann, S.; Cherkouk, A.; Brendler, V.
Abstract
I. EINLEITUNG
Für eine umfassende Sicherheitsbewertung der geologi-schen Tiefenlagerung hochradioaktiver Abfälle müssen verschiedene Aspekte berücksichtigt werden. Neben den geologischen, geochemischen und geophysikalischen Eigen-schaften spielt der Einfluss von natürlich vorkommenden Mikroorganismen im umgebenden Wirtsgestein und im Verfüllmaterial eine entscheidende Rolle in der Umgebung eines solchen Endlagers. Tongesteine sind potenzielle Wirts-gesteine für die Endlagerung dieser Abfälle, während Ben-tonite als Verfüllmaterial nicht nur für ein Endlager in Ton-gesteinen, sondern auch in kristallinen Gesteinen vorgesehen sind. Wenn im ungünstigsten Fall Wasser in das Endlager eindringt, können Radionuklide aus den Abfallbehältern austreten und mit den Mikroorganismen interagieren. Dies kann z. B. zu Veränderungen der chemischen Speziation oder des Oxidationszustandes der Metallionen führen.
II. ERGEBNISSE UND DISKUSSION
Unter endlagerrelevanten Bedingungen stellen Desul-fosporosinus spp. wichtige Vertreter der sulfatreduzierenden anaeroben Bakterien dar, welche sowohl in Tonformatio-nen als auch im Verfüllmaterial Bentonit vorkommen (Bagnoud et al. 2016, Matschiavelli et al. 2019). Verschie-dene Studien zeigen, dass sie eine wichtige Rolle in den mik-robiellen Gemeinschaften dieser Umgebung spielen. Ein mit den isolierten Arten eng verwandter Mikroorganismus ist Desulfosporosinus hippei DSM 8344T (Vatsurina et al. 2008). Daher wurde dieses Bakterium ausgewählt, um des-sen Wechselwirkungen mit Uran(VI) zu untersuchen, insbe-sondere im Hinblick auf die Reduktion zum weniger mobi-len Uran(IV), welches günstige Eigenschaften wie eine gerin-gere Mobilität aufweist und damit eine verbesserte Rückhal-tung des Radionuklids im Wirtgestein ermöglicht wird.
Zeitabhängige Reduktionsexperimente in künstlichem Opalinuston-Porenwasser (Wersin et al. 2011) mit einer Uran(VI)-Konzentration von 100 µM bei einem pH von 5.5 zeigten eine Abnahme der Uran(VI)-Konzentrationen von ca. 80 % aus den Überständen innerhalb von 48 h. Zugehö-rige UV/Vis-Messungen der aufgelösten Zellpellets liefern einen eindeutigen Nachweis des gebildeten Uran(IV). Der Anteil dieser Oxidationsstufe am zellgebundenen Uran steigt nach einer Woche auf bis zu 40 % an. Daher ist ein kombi-nierter Sorptions-Reduktionsprozess ein möglicher Wech-selwirkungsmechanismus für dieses Bakterium.
Zeitaufgelöste laserinduzierte Lumineszenzspektrosko-pie zeigt die Anwesenheit von zwei Uran(VI)-Spezies im Überstand. Ein Vergleich mit Referenzspektren erlaubt die Zuordnung zu einem Uranyl(VI)-Laktat- und einem Uranyl(VI)-Carbonat-Komplex. Die Speziesverteilung zeigt eine Abnahme des Anteils der Laktat-Spezies mit der Zeit, während der Anteil der Carbonat-Spezies nahezu konstant bleibt.
Während der Versuche bilden sich Uranaggregate auf der Oberfläche der Zellen, welche mittels Rastertransmissi-onselektronenmikroskopie nachgewiesen werden konnten. Zusätzlich setzen die Zellen uranhaltige Vesikel als mögli-chen Abwehrmechanismus gegen die Verkrustung der Zellen frei.
Darüber hinaus bestätigten HERFD-XANES-Messungen die Reduktion von Uran(VI). Mit diesen Messungen konnte auch Uran(V) in den Zellpellets nachgewiesen werden. Dies ist der erste Nachweis für die Beteiligung von Uran(V) an der Uran(VI)-Reduktion durch sulfatreduzierende Mikroorga-nismen. Mit Hilfe von EXAFS-Messungen konnten zudem verschiedene zellgebundene Uranspezies nachgewiesen werden.
III. FAZIT
Die Ergebnisse dieser Studie tragen dazu bei, bestehende Lücken in einem umfassenden Sicherheitskonzept für ein Endlager für hochradioaktive Abfälle in Tongestein zu schließen. Darüber hinaus liefert diese Studie neue Erkennt-nisse über die Wechselwirkungen sulfatreduzierender Mik-roorganismen mit Uran(VI) und zeigen eine verbesserte Rückhaltung des Radionuklids durch eine Reduktion zum weniger mobilen Uran(IV), wodurch dessen Rückhaltung verbessert wird.
IV. LITERATURVERZEICHNIS
Bagnoud A., Chourey K., Hettich R., De Bruijn I., Andersson A. F., Leupin O. X., Schwyn B., Bernier-Latmani R.: Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock, Nature Communications, 2016, 7, 1-10.
Matschiavelli N., Kluge S., Podlech C., Standhaft D., Grathoff G., Ikeda-Ohno A., Warr L. N., Chukharkina A., Arnold T., Cherkouk A.: The year-long development of microorganisms in uncompacted Bavarian bentonite slurries at 30 °C and 60 °C, En-vironmental Science & Technology, 2019, 53, 10514-10524.
Vatsurina A., Badrutdinova D., Schumann, P., Spring S., Vainshtein M.: Desulfosporosinus hippei sp. nov., a mesophilic sulfate-reducing bacterium isolated from permafrost, International Jour-nal of Systematic and Evolutionary Microbiology, 2008, 58, 5, 1228-1232.
Wersin P., Leupin O. X., Mettler S., Gaucher E. C., Mäder U., De Cannière P., Vinsot A., Gäbler H. E., Kunimaro T., Kiho K., Eichinger L.: Biogeochemical processes in a clay formation in situ experiment: Part A - Overview, experimental design and wa-ter data of an experiment in the Opalinus Clay at the Mont Terri Underground Research Laboratory, Switzerland, Applied Geo-chemistry, 2011, 26, 6, 931-953.
Keywords: Mikrobielle Uran(VI)-Reduktion; Sulfatreduzierende Bakterien; Endlagerung
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Lecture (Conference)
Tage der Standortauswahl, 18.-19.04.2024, Goslar, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38903
SE(3)-Transformers for predicting the electronic structure of hydrogen molecules
Abstract
In this work, we demonstrate the efficacy of a neural network model
implemented as the Materials Learning Algorithms (MALA) package
in predicting the electronic structure of a system of hydrogen molecules
under various pressure and temperature conditions across the molecular liquid-solid phase boundary, demonstrating the potential of our
methods for molecular systems. Additionally, we investigate the use
of SE(3)-Transformer Graph Neural Networks to improve the generalizability and extrapolation capabilities of our models. Our results
indicate that the MALA framework provides a powerful and efficient
tool for accelerating Kohn-Sham density functional theory calculations
in molecular systems. This work paves the way for future research in
developing advanced machine-learning algorithms for accelerating electronic structure calculations both accurately and efficiently.
Keywords: MALA; DFT; GNN; SE(3); Equivariant; Neural Networks; Electronic Structure
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Lecture (Conference)
DPG Spring Meeting, 18.-21.03.2024, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38901
Metalloid-doping in SMoSe Janus layers: first-principles study on efficient catalysts for the hydrogen evolution reaction
Vallinayagam, M.; Karthikeyan, J.; Posselt, M.; Devaraj, M.; Zschornak, M.
Abstract
B, Si, and Ge dopants are inserted into SMoSe Janus layers (JLs) at Mo, S, and Se as well as at interstitial sites. Spin-polarized density functional theory calculations are employed to investigate the modified structural and electronic properties of the layers, the energetics of dopant incorporation, and the effect of doping on the interaction of the two-dimensional material with hydrogen. The detailed structural analysis exposes the influence of dopant atomic sizes on lattice distortion. The formation energy Ef of dopant X (X = B, Si, and Ge) at substitutional and interstitial sites is studied for two different chemical environments: (i) bulk X – or X-rich conditions, and (ii) dimer X2 – or X-poor conditions. It is found that under X-poor conditions, the stability of the dopants is always higher. Doping at the S site is energetically most favored, with EBf < ESif < EGef . The electron redistribution in the JLs due to the presence of dopants is explored using Bader analysis. Atomic sites with a number of electrons different from that on atoms in pristine SMoSe JLs may be potential hydrogen traps and are therefore interesting for the hydrogen evolution reaction (HER). Consequently, the interaction of H atoms with these sites is studied and the H adsorption energy is calculated. While pristine SMoSe JLs repel H, several attractive sites are found in the vicinity of the dopant atoms. In order to quantify the feasibility of the doped SMoSe JLs for use as a catalyst for the HER, the free adsorption energy is determined. The data show that all dopants may improve SMoSe for HER applications. The most favorable sites are B at S and Se, Si at Mo and S, and Ge at Mo and S. In particular, adsorption and desorption of H on B-doped (at S and Se sites) and on Ge doped (at an Mo site) JLs may be rapid. The present results demonstrate the potential of metalloid doped , SMoSe JLs as efficient HER catalysts.
Keywords: 2D materials; SMoSe Janus structures; metalloid doping; first-principle study; hydrogen evolution reaction
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Journal of Materials Chemistry A 12(2024), 7742-7753
DOI: 10.1039/d3ta07243f
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-38900
Data publication: Ion-beam induced compositional and structural changes of Al-Cu-Co multilayer stacks
Černičková, I.; Noga, P.; Ďuriška, L.; Kusý, M.; Novaković, M.; Potočnik, J.; Ziegenrücker, R.; Halanda, J.; Janovec, J.
Abstract
Measurement results, obtained with a CAMECA IMS 7f-auto, of an as-deposited sample and a sample after 500°C thermal treatment.
Keywords: Multilayer; Nanolayer; Heating; Ion-beam mixing; Electron microscopy; Ion irradiation
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- DOI: 10.1016/j.apsusc.2024.159962 references this (Id 38898) publication
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Ion-beam induced compositional and structural changes of Al-Cu-Co multilayer …
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-03-25 Open access
DOI: 10.14278/rodare.2775
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Sustainable methyl formate generation by dehydrogenation of green methanol over Cu_SiO₂/MgO
Beckmann, L.; Friedrich, S.; Kaiser, D.; Störr, B.; Mertens, F.; Atia, H.; Wohlrab, S.; Llorca, J.; Bertau, M.
Abstract
Copper impregnated SiO₂ and MgO catalysts were prepared, characterised, and tested for the synthesis of methyl formate (MF) from methanol by dehydrogenation. Compared to the Cu-impregnated pure oxides, MF formation was improved when SiO₂/MgO mixtures were used as support. For further comparison, a silver impregnated mixed oxide catalyst, known for its dehydrogenation ability, and a typical methanol catalyst (Cu/ZnO/Al₂O₃) were tested. Both catalysts displayed non or poorer performance under tested reaction conditions. High catalytic activity was assigned, besides the Cu content, to the presence of both medium acidic and basic sites. At 240 °C and 1 bar, the highest MF yield of 34 % has been obtained with the mixture of oxides containing the highest MgO ratio of 35 mol%. By exposing the prepared catalyst to a methanol/water mixture (36 wt% water), methanol conversion drops to 5 %, but compared to the reference Cu/ZnO/Al₂O₃ catalyst, two times the selectivity towards MF was obtained. With respect to sustainable technology development, direct coupling of green methanol synthesis from CO₂/H₂ gas feed and MF production without water removal is not recommended, since the yield to MF is below 2 % in this case.
Keywords: Synthetic fuel; Carbon utilization; Heterogeneous catalyst; Methanol conversion; Methyl formate
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Journal of Industrial and Engineering Chemistry (2024)
DOI: 10.1016/j.jiec.2024.03.026
Permalink: https://www.hzdr.de/publications/Publ-38897
Ion-beam induced compositional and structural changes of Al-Cu-Co multilayer stacks
Černičková, I.; Noga, P.; Ďuriška, L.; Kusý, M.; Novaković, M.; Potočnik, J.; Ziegenrücker, R.; Halanda, J.; Janovec, J.
Abstract
The present work deals with the investigation of ion-beam assisted annealing/mixing effects on compositional and structural changes in Al-Cu-Co multilayers. 800 nm thick Al₆₄Cu₂₀Co₁₆ multilayers prepared by magnetron sputtering deposition, consisting of 28 successive single-metal Al-, Cu-, and Co-nanolayers were treated by thermal annealing at 300°C, 400°C, or 500°C as well as ion irradiation by 30 MeV Cu⁵⁺ ions at fluences of 1x10¹³ to 5x10¹⁴ with an average flux of 2.38×10¹⁰ at.cm⁻²s⁻¹. The samples were characterized with SEM, EDX, XRD, and TEM including HAADF. In contrast to the original multilayer, the treated samples were found to consist of two types of alternating nanolayers. A wider coarse-grained structurally and chemically homogeneous single-phase nanolayer formed by Al₂Cu, and a narrow fine-grained two-phase nanolayer, which has a heterogeneous composite structure in which the central Co sublayer (being a residue of the original single-metal Co nanolayer) is surrounded from both sides with Al-Co sublayers, consisting of Al₉Co₂. This Co sublayer is considered to be a diffusion blocker for Al and Cu as well as hindering the movement of borders between particular nanolayers. The formation of a ternary phase in the investigated samples was not confirmed in any of the samples.
Keywords: Multilayer; Nanolayer; Heating; Ion-beam mixing; Electron microscopy; Ion irradiation
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Data publication: Ion-beam induced compositional and structural changes of …
ROBIS: 38898 HZDR-primary research data are used by this (Id 38896) publication
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Applied Surface Science 660(2024), 159962
DOI: 10.1016/j.apsusc.2024.159962
Permalink: https://www.hzdr.de/publications/Publ-38896
Cobalt-based Co3Mo3N/Co4N/Co Metallic Heterostructure as a Highly Active Electrocatalyst for Alkaline Overall Water Splitting
Liu, Y.; Wang, L.; Hübner, R.; Kresse, J.; Zhang, X.; Deconinick, M.; Vaynzof, Y.; Weidinger, I. M.; Eychmüller, A.
Abstract
Alkaline water electrolysis holds promise for large-scale hydrogen production, yet it encounters challenges like high voltage and limited stability at higher current densities, primarily due to inefficient electron transport kinetics. Herein, a novel cobalt-based metallic heterostructure (Co3Mo3N/Co4N/Co) is designed for excellent water electrolysis. In operando Raman experiments reveal that the formation of the Co3Mo3N/Co4N heterointerface boosts the free water adsorption and dissociation, increasing the available protons for subsequent hydrogen production. Furthermore, the altered electronic structure of the Co3Mo3N/Co4N heterointerface optimizes ΔGH of the nitrogen atoms at the interface. This synergistic effect between interfacial nitrogen atoms and metal phase cobalt creates highly efficient active sites for the hydrogen evolution reaction (HER), thereby enhancing the overall HER performance. Additionally, the heterostructure exhibits a rapid OH- adsorption rate, coupled with great adsorption strength, leading to improved oxygen evolution reaction (OER) performance. Crucially, the metallic heterojunction accelerates electron transport, expediting the afore-mentioned reaction steps and enhancing water splitting efficiency. The Co3Mo3N/Co4N/Co electrocatalyst in the water electrolyzer delivers excellent performance, with a low 1.58 V cell voltage at 10 mAcm-2, and maintains 100% retention over 100 hours at 200 mAcm-2, surpassing the Pt/C // RuO2 electrolyzer.
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
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- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38895) publication
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Angewandte Chemie - International Edition 63(2024), e202319239
DOI: 10.1002/anie.202319239
Cited 1 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-38895
Data publication: Machine Learning-Driven Structure Prediction for Iron Hydrides
Tahmasbi, H.; Ramakrishna, K.; Lokamani, M.; Cangi, A.
Abstract
Here, we provide the training datasets and the resulting neural network potential for exploring the potential energy surfaces of the FeH system using the minima hopping method. Additionally, data for the minima structures identified in this work are included.
Related publications
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Machine Learning-Driven Structure Prediction for Iron Hydrides
ROBIS: 37800 has used this (Id 38894) publication of HZDR-primary research data
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-03-25 Open access
DOI: 10.14278/rodare.2777
Versions: 10.14278/rodare.2778
License: CC-BY-4.0
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Permalink: https://www.hzdr.de/publications/Publ-38894
Pressure-transferable neural network models for density-functional theory
Callow, T. J.; Fiedler, L.; Modine, N.; Cangi, A.
Abstract
Density functional theory (DFT) is well-known as the workhorse of electronic structure calculations in materials science and quantum chemistry. However, its applications stretch beyond these traditionally-studied fields, such as to the warm-dense matter (WDM) regime. Under WDM conditions, there are different challenges to consider (compared to ambient conditions) when using DFT. Namely, the electronic structure problem must be solved (i) for large particle numbers, (ii) for a range of temperatures, and (iii) for a range of pressures. Promising solutions were demonstrated for problems (i) and (ii) [1,2] using a recently-developed workflow to machine-learn the local density of states (LDOS) [3]. In this talk, we discuss our progress in developing a solution for problem (iii). This problem presents additional challenges because the LDOS varies quite significantly with changes in the pressure, making it a difficult problem for neural network models.
[1] L Fiedler et al., npj Comput Mater 9, 115 (2023) [2] L Fiedler et al., Phys. Rev. B 108, 125146 (2023) [3] J. A. Ellis et al., Phys. Rev. B 104, 035120 (2021)
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Lecture (Conference)
87th Annual Conference of the DPG and DPG Spring Meeting, 17.-22.03.2024, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38892
Optimization of membraneless alkaline water electrolysis
Rox, H.; Gatter, J.; Frense, E.; Schoppmann, K.; Rüdiger, F.; Krause, L.; Yang, X.; Mutschke, G.; Fröhlich, J.; Eckert, K.
Abstract
Objectives
Membraneless alkaline electrolyzer (MAEL) allow higher current densities compared to conventional designs [1] and provide very good access to the electrodes, making them ideal for research to better understand bubble formation and detachment.
Methods
In the present study both elements of a MAEL, porous electrodes and cell geometry, are optimized individually. For the geometrical optimization, CFD and current simulations were performed to obtain an optimized cell geometry that ensures constant conditions for the water splitting reaction over the entire electrode area. A three-electrode cell was used to perform parametric studies of HER on porous electrodes [2] and functionalized surfaces [3]. Therefore, Particle Image Velocimetry and Shadowgraphy were used to systematically study the influence of the electrode surface and the electrolyte flow as driving force for an effective H2 and O2 separation in a MAEL.
Results & Conclusions
It is shown that below a critical Recrit the evolving bubbles are stuck on the porous electrodes and lead to a blockage of the electrochemical active sites and to an increase of the cell potential. At the optimal flow rate to current density ratio high gas purity and overall efficiency were observed. Importantly, this study presented an experimental framework that guides the electrode and cell design of MAELs and analyzes their performance limits.
Literature
[1] D.V. Esposito, Joule. 2017, 1, 651-658.
[2] H. Rox et al., Int. J. Hydrog. Energy. 2023, 48, 2892-2905.
[3] L. Krause et al., ACS Applied Materials & Interfaces. 2023, 15, 14, 18290-18299.
Keywords: Alkaline electrolysis; Membraneless electrolyzer; Bubble dynamics; Shadowgraphy; PIV
Involved research facilities
- Data Center
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Lecture (Conference)
HydrogenDays 2024, 21.03.2024, Prague, Czech republic
Permalink: https://www.hzdr.de/publications/Publ-38888
Towards tailoring hydrophobic interaction with uranyl(VI) oxygen for C-H activation
Tsushima, S.; Kretzschmar, J.; Doi, H.; Okuwaki, K.; Kaneko, M.; Mochizuki, Y.; Takao, K.
Abstract
Bovine serum albumin (BSA) has a uranyl(VI) binding hotspot where uranium is tightly bound by three carboxylates. Uranyl oxygen is “soaked” into the hydrophobic core of BSA. Isopropyl hydrogen of Val is trapped near UO22+ and upon photoexcitation, C–H bond cleavage is initiated. A unique hydrophobic contact with “yl”-oxygen, as observed here, can be used to induce C-H activation.
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Chemical Communications 60(2024), 4769-4772
DOI: 10.1039/D4CC01030B
Permalink: https://www.hzdr.de/publications/Publ-38885
Optimization of Heat and Mass Transfer via Nano/Micro-Structured Surfaces: utilizing energy barriers between states and “semi-dimensional reduction”
Ding, W.; Zhang, J.; Zhao, P.; Reinecke, S.; Hampel, U.
Abstract
Energy barriers inhibit the transition of a system from one state to another. This is evident in phenomena such as bubble nucleation during boiling, droplet expansion and contraction when it impacts a heated surface, and also cavitation. In this presentation, we will elucidate our insights and understanding of the exploitation of energy barriers post-state transition to augment heat and mass transfer in various processes. Specifically, in processes like bubble nucleation in boiling, the high energy required for nucleation (attributable to the energy barrier) triggers rapid bubble expansion and results in a semi-2D microlayer, just a few micrometers thin, on the surface. This can be viewed as a typical semi-dimensional reduction effect, transitioning a part of system from 3D to 2D. As a result, this thin liquid layer brings high efficiency on heat transfer. A similar phenomenon occurs when a droplet impacts a heated surface. Following impact, the droplet’s expansion and contraction on the surface incite capillary waves that propagate along the droplet interface, inducing a semi-1D, prickle-like jet along the droplet’s axis on the top side. This jet disrupts the vapor film beneath the droplet, expelling the vapor and delaying the Leidenfrost point. As a one more thing, cavitation, one of the most typical cases of ‘dimensional reduction’, utilizes a reduction from 3D to 0D and also the large energy barrier for bubble nucleation. Following bubble collapse, the local temperature and pressure reach 5000 K and ~ Mpa, respectively. Combined with O3, this effect facilitates a highly efficient oxidation process.
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Invited lecture (Conferences)
4th Conference on Micro FLow and Interfactial Phenomena (µFIP) 2024, 21.-24.06.2024, The Hong Kong Polytechnic University, HongKong, China
Permalink: https://www.hzdr.de/publications/Publ-38883
Applying an Explicit Temperature-dependent Generalized Gradient Approximation to Warm Dense Matter: Thermal PBE
Ramakrishna, K.; Lokamani, M.; Cangi, A.
Abstract
Using the methodology of Kozlowski et al. [arXiv 2308.03319 (2023)] to extend the temperature dependence of the Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation, we implement the thermal equivalent of the PBE functional (tPBE) in a plane wave code to study the equilibrium properties such as energies, pressures, and forces of warm dense matter using density functional theory and linear-response properties such as the electrical conductivity, dynamic structure factor using time-dependent density functional theory. In addition, we compare the effects with the thermal equivalent of LDA and the ground-state LDA and PBE functionals.
Keywords: Density functional theory; Matter under Extreme Conditions
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Lecture (Conference)
APS March Meeting 2024, 04.-08.03.2024, Minneapolis, USA
Permalink: https://www.hzdr.de/publications/Publ-38880
Structure prediction of iron hydrides across pressure range with transferable machine-learned interatomic potential
Tahmasbi, H.; Ramakrishna, K.; Lokamani, M.; Cangi, A.
Abstract
Recently, machine-learned interatomic potentials (ML-IAPs) have emerged as a solution to the computational limitations of density functional theory (DFT)-based approaches, enabling the modeling of large systems with hundreds or even thousands of atoms. Here, we demonstrate the efficacy of automated and systematic methods for training and validating transferable ML-IAPs through global optimization techniques.
We utilize the PyFLAME code [1] to construct a highly transferable neural network potential. With this accurate and fast potential, we systematically investigate the potential energy surfaces (PESs) of FeH through global sampling using the minima hopping method [2] over a wide range of pressures. This comprehensive exploration enables us to predict stable and metastable iron hydrides from 0 to 100 GPa.
Our analysis reveals the experimentally observed global minimum structures -the dhcp, hcp, and fcc phases- in agreement with previous studies. Furthermore, our exploration of the PESs of FeH at various pressures uncovers numerous interesting modifications and stacking faults of the aforementioned phases, including several remarkably low-enthalpy structures.
This investigation led to the discovery of a rich array of novel stoichiometric crystal phases of FeH across a wide pressure range, confirming the presence of coexisting regions containing known FeH structures. This finding demonstrates one of the benefits of using large-scale structure prediction techniques to uncover the PESs of materials.
[1] H. Mirhosseini, H. Tahmasbi, S. R. Kuchana, S. A. Ghasemi, and T. D. Kühne, Comput. Mater. Sci. 197, 110567 (2021).
[2] M. Amsler and S. Goedecker, J. Chem. Phys. 133, 224104 (2010).
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Lecture (Conference)
APS MArch meeting 2024, 04.-08.03.2024, Minneapolis, US
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Live Iterative Ptychography
Weber, D.; Ehrig, S.; Schropp, A.; Clausen, A.; Achilles, S.; Hoffmann, N.; Bussmann, M.; Dunin-Borkowski, R.; Schroer, C. G.
Abstract
We demonstrate live-updating ptychographic reconstruction with ePIE, an iterative ptychography method, during ongoing data acquisition. The reconstruction starts with a small subset of the total data, and as the acquisition proceeds the data used for reconstruction is extended. This creates a live-updating view of object and illumination that allows monitoring the ongoing experiment and adjusting parameters with quick turn-around. This is particularly advantageous for long-running acquisitions. We show that such a gradual reconstruction yields interpretable results already with a small subset of the data. We show simulated live processing with various scan patterns, parallelized reconstruction, and real-world live processing at the hard X-ray ptychographic nanoanalytical microscope PtyNAMi at the PETRA III beamline.
Keywords: ptychography; X-ray microscopy
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Microscopy and Microanalysis 30(2024), 103-117
DOI: 10.1093/mam/ozae004
Permalink: https://www.hzdr.de/publications/Publ-38877
Effect of Ba(II), Eu(III), and U(VI) on rat NRK-52E and human HEK-293 kidney cells in vitro
Senwitz, C.; Butscher, D.; Holtmann, L.; Vogel, M.; Steudtner, R.; Drobot, B.; Stumpf, T.; Barkleit, A.; Heller, A.
Abstract
Heavy metals pose a potential health risk to humans when they enter the organism. Renal excretion is one of the elimination pathways and, therefore, investigations with kidney cells are of particular interest. In the present study, the effects of Ba(II), Eu(III), and U(VI) on rat and human renal cells were investigated in vitro. A combination of microscopic, biochemical, analytical, and spectroscopic methods was used to assess cell viability, cell death mechanisms, and intracellular metal uptake of exposed cells as well as metal speciation in cell culture medium and inside cells.
For Eu(III) and U(VI), cytotoxicity and intracellular uptake are positively correlated and depend on concentration and exposure time. An enhanced apoptosis occurs upon Eu(III) exposure whereas U(VI) exposure leads to enhanced apoptosis and (secondary) necrosis. In contrast to that, Ba(II) exhibits no cytotoxic effect at all and its intracellular uptake is time-independently very low. In general, both cell lines give similar results with rat cells being more sensitive than human cells.
The dominant binding motifs of Eu(III) in cell culture medium as well as cell suspensions are (organo-) phosphate groups. Additionally, a protein complex is formed in medium at low Eu(III) concentration. In contrast, U(VI) forms a carbonate complex in cell culture medium as well as each one phosphate and carbonate complex in cell suspensions. Using chemical microscopy, Eu(III) was localized in granular, vesicular compartments near the nucleus and the intracellular Eu(III) species equals the one in cell suspensions.
Overall, this study contributes to a better understanding of the interactions of Ba(II), Eu(III), and U(VI) on a cellular and molecular level. Since Ba(II) and Eu(III) serve as inactive analogs of the radioactive Ra(II) and Am(III)/Cm(III), the results of this study are also of importance for the health risk assessment of these radionuclides.
Keywords: Cytotoxicity; Radionuclides; Kidney cells; Heavy metal speciation; TRLFS; Chemical microscopy
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Science of the Total Environment 923(2024), 171374-171394
DOI: 10.1016/j.scitotenv.2024.171374
Permalink: https://www.hzdr.de/publications/Publ-38876
Electrical characterization of multi‑gated WSe2/MoS2 van der Waals heterojunctions
Chava, P.; Kateel, V.; Watanabe, K.; Taniguchi, T.; Helm, M.; Mikolajick, T.; Erbe, A.
Abstract
Vertical stacking of different two-dimensional (2D) materials into van der Waals heterostructures exploits the properties of individual materials as well as their interlayer coupling, thereby exhibiting unique electrical and optical properties. Here, we study and investigate a system consisting entirely of different 2D materials for the implementation of electronic devices that are based on quantum mechanical band-to-band tunneling transport such as tunnel diodes and tunnel field-effect transistors. We fabricated and characterized van der Waals heterojunctions based on semiconducting layers of WSe2 and MoS2 by employing different gate configurations to analyze the transport properties of the junction. We found that the device dielectric environment is crucial for achieving tunneling transport across the heterojunction by replacing thick oxide dielectrics with thin layers of hexagonal boronnitride. With the help of additional top gates implemented in different regions of our heterojunction device, it was seen that the tunneling properties as well as the Schottky barriers at the contact interfaces could be tuned efficiently by using layers of graphene as an intermediate contact material.
Keywords: 2d material; van der waals; heterostructure; tunneling; transistor
Related publications
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Electrical characterization of multi-gated WSe2/MoS2 van der Waals …
ROBIS: 38985 HZDR-primary research data are used by this (Id 38872) publication -
Electrical characterization of multi-gated WSe2/MoS2 van der Waals …
RODARE: 2813 HZDR-primary research data are used by this (Id 38872) publication
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Scientific Reports 14(2024), 5813
DOI: 10.1038/s41598-024-56455-x
Permalink: https://www.hzdr.de/publications/Publ-38872
Dynamics of particle attachment in a model stirred cell: A new technique to characterize and quantify particle floatability
Eftekhari, M.; Schwarzenberger, K.; Schlereth, P.; Eckert, K.
Abstract
Floatability evaluation is critical to predicting flotation results and designing a flotation flowsheet. Laboratory-scale flotation cells are commonly used to study particle floatability, but differences in cell design and governing hydrodynamics make extrapolation to industrial scale operations difficult.
In this work, a new experimental approach based on particle attachment dynamics is proposed to evaluate particle floatability. This method allows precise control of hydrodynamic conditions, visualization of attachment processes, and direct observation of the bubble surfaces. It is therefore ideal for studying attachment dynamics as a function of collector concentration, particle size and concentration, and propeller speed. In addition, it opens the possibility for future studies of the packing density of the particles at the interface and their selective attachment. By evaluating the time-dependent surface coverage as a function of bubble residence time, we illustrate its ability to predict flotation kinetics within a flotation cell. This innovative technique provides a faster, more versatile means of studying particle floatability and attachment dynamics with practical implications for flotation cell optimization.
Keywords: Floatability; Stirred cell; Particle-bubble interactions; Dynamic surface coverage; Flotation kinetics
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Minerals Engineering 210(2024), 108643
DOI: 10.1016/j.mineng.2024.108643
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Recent extensions to the NUSAR-RCS IT environment
Lehnigk, R.; Hänsch, S.; Schlegel, F.; Lucas, D.
Abstract
Due to the growing importance of Computational Fluid Dynamics (CFD) for reactor safety research, there have been activities aimed at qualifying the associated methods for many years. This entails the development and validation of models on the basis of detailed experimental data, generated in comprehensive projects. There was and is a need for development, among other things, for multiphase flows, in particular for accident scenarios in the reactor coolant system. In order to be able to use the model developments and validation data generated throughout various publicly funded projects in the long term, these are carried out using the software provided by the OpenFOAM Foundation, which is thereby qualified for application. The project presented here is funded by the German Federal Ministry for Environment, Nature Conservation, Nuclear Safety and Consumer Protection (project number 1501658) and has the objective of gathering and maintaining addon software and simulation setups from partner institutions in a common repository, referred to as "Nuclear Safety Repository for OpenFOAM Foundation Software for Reactor Cooling System (NUSAR-RCS)". To this end, a GitLab-based IT environment has been developed that fosters collaborative developments and facilitates the maintenance of results from completed projects. The talk will highlight some recent additions to the environment. The first part is dedicated to a Python package, which, among other things, supplies functionality for bulk processing of simulation results, e.g. to extract global information on the agreement between simulation and experiment using statistical key figures. The second part will present efforts of making the NUSAR-RCS software more portable by means of containerization using Apptainer images.
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Lecture (Conference)
35th German CFD Network of Competence Meeting, 12.-13.03.2024, München, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-38870
Repulsive Tomonaga-Luttinger liquid in the quasi-one-dimensional alternating spin-1/2 antiferromagnet NaVOPO4
Islam, S. S.; Mukharjee, P. K.; Biswas, P. K.; Telling, M.; Skourski, Y.; Ranjith, K. M.; Baenitz, M.; Inagaki, Y.; Furukawa, Y.; Tsirlin, A. A.; Nath, R.
Abstract
We probe the magnetic field-induced Tomonaga-Luttinger liquid (TLL) state in the bond-alternating spin-1/2 antiferromagnetic (AFM) chain compound NaVOPO4 using thermodynamic as well as local μSR and 31P NMR probes down to mK temperatures in magnetic fields up to 14 T. The μSR and NMR relaxation rates in the gapless TLL regime decay slowly following characteristic power-law behavior, enabling us to directly determine the interaction parameter K as a function of the magnetic field. These estimates are crosschecked using magnetization and specific heat data. The field-dependent K lies in the range of 0.4 < K < 1 and indicates the repulsive nature of interactions between the spinless fermions, in line with the theoretical predictions. This renders NaVOPO4 the first experimental realization of TLL with repulsive fermionic interactions in hitherto studied S = 1/2 bond-alternating AFM-AFM chain compounds.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Physical Review B 109(2024), L060406
DOI: 10.1103/PhysRevB.109.L060406
arXiv: https://arxiv.org/abs/2311.03231
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38863
Field-induced magnetic transitions in the highly anisotropic ferrimagnet ErFe5Al7 studied by high-field x-ray magnetic dichroism
Yamamoto, S.; Gorbunov, D.; Prokhnenko, O.; Weschke, E.; Miyata, A.; Diaz-Ortega, I. F.; Strohm, C.; Duc, F.; Henriques, M. S.; Gazizulina, A.; Uhlarz, M.; Mathon, O.; Andreev, A. V.; Nojiri, H.; Wosnitza, J.
Abstract
We present a comprehensive study of the magnetic properties of the strongly anisotropic ferrimagnet ErFe5Al7 in pulsed magnetic fields up to 30 T applied along the hard magnetization axis within the basal plane of the tetragonal lattice around the compensation temperature (Tcomp). Macroscopic measurements showed two anomalies at about 8 T and 25 T in a small temperature range around Tcomp. High-field x-ray magnetic circular dichroism (XMCD) data at the Er M5- and the Fe L3-edge resonances provide insight into the element-selective magnetization processes, revealing a coherent rotation of Er 4f and Fe 3d moments, with stepwise jumps including an unexpected one from an easy to a hard magnetization axis. XMCD at the Er L3-edge resonance elucidates the role of Er 5d electrons in coupling the Er 4f and the Fe 3d moments. Finally, an in-plane anisotropy constant was evaluated from a simulation of the magnetization process at temperatures well below Tcomp using a two-sublattice model.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Physical Review B 109(2024), 094404
DOI: 10.1103/PhysRevB.109.094404
Downloads
- Secondary publication expected from 05.03.2025
Permalink: https://www.hzdr.de/publications/Publ-38862
Pressure-tuned quantum criticality in the large-D antiferromagnet DTN
Povarov, K.; Graf, D. E.; Hauspurg, A.; Zherlitsyn, S.; Wosnitza, J.; Sakurai, T.; Ohta, H.; Kimura, S.; Nojiri, H.; Garlea, V. O.; Zheludev, A.; Paduan-Filho, A.; Nicklas, M.; Zvyagin, S.
Abstract
Strongly correlated spin systems can be driven to quantum critical points via various routes. In particular, gapped quantum antiferromagnets can undergo phase transitions into a magnetically ordered state with applied pressure or magnetic field, acting as tuning parameters. These transitions are characterized by z = 1 or z = 2 dynamical critical exponents, determined by the linear and quadratic low-energy dispersion of spin excitations, respectively. Employing high-frequency susceptibility and ultrasound techniques,we demonstrate that the tetragonal easy-plane quantum antiferromagnet NiCl2 ⋅ 4SC(NH2)2 (aka DTN) undergoes a spin-gap closure transition at about 4.2 kbar, resulting in a pressure-induced magnetic ordering. The studies are complemented by high-pressure electron-spin-resonance measurements confirming the proposed scenario. Powder neutron diffraction measurements revealed that no lattice distortion occurs at this pressure and the high spin symmetry is preserved, establishing DTN as a perfect platform to investigate z = 1 quantum critical phenomena. The experimental observations are supported by DMRG calculations, allowing us to quantitatively describe the pressure-driven evolution of critical fields and spin-Hamiltonian parameters in DTN.
Involved research facilities
- High Magnetic Field Laboratory (HLD)
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Nature Communications 15(2024), 2295
DOI: 10.1038/s41467-024-46527-x
arXiv: https://arxiv.org/abs/2306.15450
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38861
Data publication: A deep-learning-based surrogate model for Monte-Carlo simulations of the linear energy transfer in primary brain tumor patients treated with proton-beam radiotherapy
Starke, S.; Kieslich, A. M.; Palkowitsch, M.; Hennings, F.; Troost, E. G. C.; Krause, M.; Bensberg, J.; Hahn, C.; Heinzelmann, F.; Bäumer, C.; Lühr, A.; Timmermann, B.; Löck, S.
Abstract
This repository contains the outputs and result data of our deep-learning-based experiments for the approximation of Monte-Carlo-simulated linear energy transfer distributions, which build the foundation for the corresponding article.
The Pytorch checkpoint of our finally chosen SegResNet architecture trained on the UPTD dose distributions is located at dd_pbs/Dose-LETd/clip_let_below_0.04/segresnet/all_trainvalid_data/training/lightning_logs/version_6358843/checkpoints/last.ckpt.
Moreover, we provide an exemplary data sample from a water phantom for trying our analysis pipeline.
Keywords: proton-beam therapy; relative biological effectiveness; linear energy transfer; NTCP models; deep learning; brain tumor
Involved research facilities
- OncoRay
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Reseach data in the HZDR data repository RODARE
Publication date: 2024-03-15 Open access
DOI: 10.14278/rodare.2763
Versions: 10.14278/rodare.2764
License: CC-BY-4.0
Downloads
Permalink: https://www.hzdr.de/publications/Publ-38860
A guide to advanced MRI processing for clinical glioma research
Clement, P.; Beun, S.; Arzanforoosh, F.; Castellaro, M.; Debiasi, G.; Emblem, K. E.; Fuster-Garcia, E.; Grech-Sollars, M.; Kallehauge, J. F.; Lazen, P.; Nunes, R. G.; Ozturk-Isik, E.; Pinto, J.; Piskin, S.; Robinson, S. D.; Siugzdaite, R.; Sollmann, N.; Fløgstad Svensson, S.; Warnert, E. A. H.; Wiegers, E.; Petr, J.; Hangel, G.
Abstract
Todate,multipleadvancedmagneticresonanceimaging(MRI)methodsbeyondconventionalqualitativestructuralimagingforthediagnosis,prognosis,andtreatmentfollow-upofgliomahavedemonstratedtheirutilityforclinicalstudies.However,thesemethodsoftenrelyoncomplexoff-scannerprocessingtoyieldthemostinformationandtoextractquantitativebiomarkers,limitingtheirpracticaluseforstudies,aswellastheirclinicaltranslation.Whilecommunity-drivensoftwaresolutionsexistfortheseadvancedMRImethods,manyaspiringclinicalresearchersfacechallengesinacquiringthenecessaryknowledgetoeffectivelyapplythesetools.Thisguide,aninitiativeoftheGliomaMRimaging2.0network(GliMR),aimstoprovideanoverviewofexistingsolutions,communities,andrepositorieswiththeultimategoalofenablingstandardization,openscience,andreproduciblequantitativeimagingstudiesofgliomas.Yet,mostofthereviewedtoolsandapproachestoimagedataanalysesmayalsobeusedinthecontextofstudiesondiseasesotherthanglioma.
Involved research facilities
- PET-Center
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Contribution to WWW
https://osf.io/preprints/psyarxiv/rh4md
DOI: 10.31234/osf.io/rh4md
Permalink: https://www.hzdr.de/publications/Publ-38856
NuScale SLB analysis with TrioCFD/ATHLET/DYN3D
Grahn, A.; Diaz Pescador, E.; Bilodid, Y.; Kliem, S.
Abstract
The small modular reactor (SMR) NuScale has been modelled in the framework of the EURATOM McSAFER project. The main objective was to demonstrate the feasibility of a coupled approach using a thermal-hydraulic system code (ATHLET), a 3-D reactor dynamics code (DYN3D) and a CFD software (TrioCFD) to model the whole primary coolant loop and large parts of the secondary side of the plant, including the downcomer-integrated, helical-coiled steam generators (SG) and the decay heat removal system (DHRS). The 3-D neutronic calculation of the reactor core was performed with a cross-section library developed with Serpent, and the coolant flow in the downcomer and lower plenum of the pressure vessel was analyzed by CFD. A double-ended, non-isolatable steam line break sequence served as a test case for the code coupling. Simulation results at steady-state show agreement with the reference values from the Design certification Application (DCA) report. The transient simulation shows that the rapid depressurization and boil-off with high steam rates towards the break lead to enhanced primary-to-secondary heat removal. However, the symmetrical arrangement of SGs in the NuScale reactor limits the coolant temperature reduction at the core inlet to prevent a possible power excursion which highlights the inherent safety of this reactor design.
Keywords: small modular reactors; steam line break; thermal-hydraulics; reactor dynamics; system codes; computational fluid dynamics
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Lecture (Conference)
Workshop on Core and Plant Simulation with an Emphasis on Fuel Behaviour in Light Water Reactor based Small Modular Reactors, 27.-29.02.2024, Wien, Österreich
Permalink: https://www.hzdr.de/publications/Publ-38855
Strain-modulated defect engineering of two-dimensional materials
Santra, P.; Ghaderzadeh, S.; Ghorbani Asl, M.; Komsa, H.-P.; Besley, E.; Krasheninnikov, A.
Abstract
Strain- and defect-engineering are two powerful approaches to tailor the opto-electronic properties of two-dimensional (2D) materials, but the relationship between applied mechanical strain and behavior of defects in these systems remains elusive. Using first-principles calculations, we study the response to external strain of $h$-BN, graphene, MoSe$_2$, and phosphorene, four archetypal 2D materials, which contain substitutional impurities. We find that the formation energy of the defect structures can either increase or decrease with bi-axial strain, depending on the atomic radius of the impurity atom, which can be larger or smaller than that of the host atom. Analysis of the strain maps indicates that this behaviour is associated with the compressive or tensile local strains produced by the impurities that interfere with the external strain. We further show that the change in the defect formation energy is related to the change in elastic moduli of the 2D materials upon introduction of impurity, which can correspondingly increase or decrease. The discovered trends are consistent across all studied 2D materials and are likely to be general. Our findings open up opportunities for combined strain- and defect-engineering to tailor the opto-electronic properties of 2D materials, and specifically, the location and properties of single-photon emitters.
Keywords: defects; strain; 2D materials; first-principles calculations
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
Related publications
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38854) publication
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npj 2D Materials and Applications 8(2024), 33
DOI: 10.1038/s41699-024-00472-x
Permalink: https://www.hzdr.de/publications/Publ-38854
Developing blood-brain barrier arterial spin labelling as a non-invasive early biomarker of Alzheimer’s disease (DEBBIE-AD): a prospective observational multicohort study protocol
Padrela, B.; Mahroo, A.; Tee, M.; Sneve, M. H.; Moyaert, P.; Geier, O.; Kuijer, J. P. A.; Beun, S.; Nordhøy, W.; David Zhu, Y.; Buck, M. A.; Hoinkiss, D. C.; Konstandin, S.; Huber, J.; Wiersinga, J.; Rikken, R.; de Leeuw, D.; Grydeland, H.; Tippett, L.; Cawston, E. E.; Ozturk-Isik, E.; Linn, J.; Brandt, M.; Tijms, B. M.; van de Giessen, E. M.; Muller, M.; Fjell, A.; Walhovd, K.; Bjørnerud, A.; Pålhaugen, L.; Selnes, P.; Clement, P.; Achten, E.; Anazodo, U.; Barkhof, F.; Hilal, S.; Fladby, T.; Eickel, K.; Morgan, C.; Thomas, D. L.; Petr, J.; Günther, M.; Mutsaerts, H. J. M. M.
Abstract
Introduction Loss of blood-brain barrier (BBB) integrity is
hypothesised to be one of the earliest microvascular signs
of Alzheimer’s disease (AD). Existing BBB integrity imaging
methods involve contrast agents or ionising radiation, and
pose limitations in terms of cost and logistics. Arterial
spin labelling (ASL) perfusion MRI has been recently
adapted to map the BBB permeability non-invasively. The
DEveloping BBB-ASL as a non-Invasive Early biomarker
(DEBBIE) consortium aims to develop this modified
ASL-MRI technique for patient-specific and robust BBB
permeability assessments. This article outlines the study
design of the DEBBIE cohorts focused on investigating
the potential of BBB-ASL as an early biomarker for AD
(DEBBIE-AD).
Methods and analysis DEBBIE-AD consists of a
multicohort study enrolling participants with subjective
cognitive decline, mild cognitive impairment and AD, as
well as age-matched healthy controls, from 13 cohorts.
The precision and accuracy of BBB-ASL will be evaluated
in healthy participants. The clinical value of BBB-ASL will
be evaluated by comparing results with both established
and novel AD biomarkers. The DEBBIE-AD study aims to
provide evidence of the ability of BBB-ASL to measure BBB
permeability and demonstrate its utility in AD and ADrelated pathologies.
Ethics and dissemination Ethics approval was obtained
for 10 cohorts, and is pending for 3 cohorts. The results of
the main trial and each of the secondary endpoints will be
submitted for publication in a peer-reviewed journal.
Involved research facilities
- PET-Center
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BMJ Open 14(2024)3, e081635
DOI: 10.1136/bmjopen-2023-081635
Permalink: https://www.hzdr.de/publications/Publ-38853
Experiences from first time RSE class at the Computer Science Faculty of TU Dresden
Abstract
For the first time, Introduction to Research Software Engineering was offered as a class in the Computer Science faculty of TU Dresden during this winter semester (2023/24) (https://tu-dresden.de/ing/informatik/smt/cgv/studium/lehrveranstaltungen/ws2324/RSE/index). This talk will briefly cover the content, feedback from students and own observations as well as ideas how to continue and extend the class in the future.
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Lecture (Conference)
deRSE24 - Conference for Research Software Engineering in Germany, 05.-07.03.2024, Würzburg, Germany
Permalink: https://www.hzdr.de/publications/Publ-38851
Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.] [351.]