Current-induced unidirectional magnetoresistance in FeRh/Pt bilayers*

Antiferromagnetic (AFM) spin-orbit torque oscillators are important due to potential applications ranging from magnetic random-access memory to THz emitters. However, AFM spin-torque oscillators operate in the THz-range, and direct observation of THz magnetization dynamics is difficult. Previously, in ferromagnetic spin-torque oscillators, current-induced unidirectional magnetoresistance (UMR) signals accompanied the emission of microwave radiation at the ferromagnetic resonance frequency [1,2], which implies that observations of UMR may provide indirect evidence of AFM-resonance. Here we present transport results on magnetron sputtered AFM FeRh/Pt films, fabricated into nanowire geometries. A current-induced UMR is observed, in addition to anisotropic magnetoresistance effects. These findings suggest a route toward designing AFM spin-orbit torque oscillators.
[1] Langenfeld et al. Appl. Phys. Lett. 108, 192402 (2016)
[2] Yasuda et al. Phys. Rev. Lett. 117, 127202 (2016)