Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Combining semiconducting and ferromagnetic properties, dilute ferromagnetic semiconductors (DFS) have been under intensive investigation for more than two decades. Mn doped III-V compound semiconductors have been regarded as the prototype of the type. In this contribution, we will show how the implantation technique, a standard method for doping Si in microelectronic industry, can be utilized in fabricating and deeper understanding of DFS. First, ion implantation followed by pulsed laser melting (II-PLM) provides an alternative to the widely used low-temperature molecular beam epitaxy (LTMBE) approach in the preparation of diverse DFS. The prepared DFS materials exhibit pronounced magnetic anisotropy, large X-ray magnetic circular dichroism as well as anomalous Hall effect and magnetoresistance [1-9]. Going beyond LT-MBE, II-PLM is successful to bring two new members, GaMnP and InMnP, into the family of III-Mn-V. Both GaMnP and InMnP films show clear signatures of ferromagnetic coupling and an insulating behavior. Second, helium ions can be used to precisely compensate the holes while keeping the Mn concentration constant [10-12]. We monitor the change of Curie temperature (TC) and conductivity. For a broad range of samples including (Ga,Mn)As and (Ga,Mn)(As,P) with various Mn and P concentrations, we observe a smooth decrease of TC over a wide temperature range with carrier compensation while the conduction is changed from metallic to insulating. In the low compensation regime, we can tune the uniaxial magnetic easy axis of (Ga,Mn)(As,P) from out-of-plane to in-plane with an isotropic-like intermediate state. These materials synthesized or tailored by ion beams provide an alternative avenue to understand how carrier-mediated ferromagnetism is influenced by localization.

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