Zero-Offset Hall: A new concept for Antiferromagnetic Spintronics

Antiferromagnets have the potential to revolutionize spintronics due to their inherently magnetic-field stable magnetic order. The tiny uncompensated magnetic moment of the locally uncompensated antiferromagnetic lattice determines not only the physics of the materials, e.g. topology of antiferromagnetic domain walls [1], but also their application potential for novel magnetoelectric random access memory (MERAM) devices [2] or
antiferromagnetic analogues to racetrack devices. The rich physics of thin film antiferromagnets can be harnessed for prospective spintronic devices given that all-electric assessment of the tiny uncompensated magnetic moment is achieved.

We put forth a new method providing all-electric access to the field-invariant magnetization of antiferromagnetic thin films [3]. This technique – zero-offset Hall – is based on the combination of Anomalous Hall effect magnetometry with dynamic spinning-current offset compensation. We show that this technique opens the scope for magnetic phenomena that can go amiss in conventional Hall measurements with stationary current direction. The adoption of this technique will therefore substantially improve the reach of lab-based transport investigations in the thriving field of antiferromagnetic spintronics and
lead to new application concepts.

On the examples or metallic IrMn and insulating Cr 2 O 3 antiferromagnetic thin films, we demonstrate, that zero-offset Hall can probe thin film magnetism at unprecedented sensitivity, which allows us to reveal previously unknown peculiarities of the physical behavior. The access to insulating magnetic films is enabled by the magnetic proximity effect of certain conductors such as Pt.

The method is not exclusive to anomalous Hall measurements. Instead, all phenomena that alter the transversal resistance, such as the topological Hall effect and the quantum Hall effects, can be studied in greatly improved detail. At the same time, the measurements are technically easy and can be realized in most laboratories making it fast to adopt. Therefore, we believe that zero-offset Hall is of strong relevance for the community of topological and spin phenomena in nanostructures.

[1] M. Bode et al., Nature Materials 5, 477 (2006)
[2] X. He et al., Nature Materials 9, 579 (2010)
[3] T. Kosub et al., Phys. Rev. Lett. 115, 097201 (2015)