Spin Transport Properties of FeRh Across its Magnetic Phase Transition

Recent discoveries in antiferromagnets (AFs) such as spin-orbit torques, spin Seebeck effects and inverse spin Hall effects have opened up new possibilities for spintronics devices.[1] Of particular interest is the equiatomic FeRh, which undergoes a temperature driven antiferromagnet-to-ferromagnet magnetic phase transition. This metallic AF is also promising for spintronics applications due to its relatively large spin-orbit coupling arising from Rh. We have grown epitaxial FeRh films on MgO (100) and patterned them into measurement devices using photolithography and ion milling. We performed anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) measurements on 20-nm-thick FeRh films at various temperatures. Our findings show a drastic suppression of both AHE and ANE signals in the AF phase. Interestingly, these non-vanishing signals are opposite in sign compared to their ferromagnetic counterparts, which may suggest changes of inherent symmetries in the electronic structure of FeRh across its magnetic phase transition.

[1] M. B. Jungfleisch et.al, Phys. Lett. A. 382, 865 (2018).