Spin Orbit Coupling Controlled Spin Pumping and Spin Hall Magnetoresistance Effects

Abstract

Effective spin mixing conductance (ESMC) across the nonmagnetic metal (NM)/ferromagnet interface, spin Hall conductivity (SHC), and spin diffusion length (SDL) in the NM layer govern the functionality and performance of pure spin current devices. It is shown that all three parameters can be tuned significantly via the spin orbit coupling (SOC) strength of the NM layer by virtue of the unique Pd1‐xPtx/Y3Fe5O12 system. Surprisingly, the ESMC is observed to increase significantly with x changing from 0 to 1.0, due to the enhanced local density of states for Pt‐rich alloys. The SHC in PdPt alloys turns out to be dominated by the skew scattering term. In particular, the skew scattering parameter has for the first time been rigorously demonstrated to increase with increasing SOC strength. Meanwhile, the SDL is found to decrease when Pd atoms are replaced by heavier Pt atoms, validating the SOC induced spin flip scattering model in polyvalent PdPt alloys. A thorough grasp of the dependence of these parameters on the SOC strength in the present work can help to develop a better theoretical graph on the physics of SOC and spin orbit torque switching, relevant to next generation spintronic devices.