Composition dependence of spin-orbit torques in PtRh/ferromagnet heterostructures

Abstract

We experimentally study the spin-orbit torque (SOT) in PtRh/heterostructures by varying the composition of PtRh alloy. By performing dc-biased spin-torque ferromagnetic resonance and second-harmonic measurements in PtxRh1?x/ferromagnet heterostructures, we find that the effective damping-like spin-torque efficiency and spin Hall conductivity are 0.18 and 3.8 × 105 ?/2e ??1 m?1 for Pt0.9Rh0.1, respectively, with a low resistivity of 46.9 µ? cm. Furthermore, current induced SOT switching in PtRh/Co is investigated. The critical current density for SOT switching decreases with an increase in the Rh composition of the PtRh alloy, which can be understood by domain wall assisted switching. Due to a large spin Hall conductivity, a relatively low resistivity, and sustainability of the high temperature process, the PtRh alloy could be an attractive spin source for SOT applications. © 2021 Author(s).