Spin Hall effect investigated by spin Hall magnetoresistance in Pt100-xAux/CoFeB systems

We studied spin Hall effect (SHE) in Pt100-xAux with various Au compositions x for Pt-Au/CoFeB systems by means of spin Hall magnetoresistance (SMR). We synthesized low resistive, flat, and highly (111)-textured Pt-Au alloy films by sputtering using low pressure Kr gas. We found that spin Hall angle (theta (SH)), spin Hall conductivity (sigma (SH)), and spin diffusion length (lambda (S)) increase by alloying Pt with Au at certain x. The enhancement of sigma (SH) is consistent with the theoretically predicted increase in the intrinsic spin Hall conductivity, however quantitatively, there are some discrepancies in theta (SH) and lambda (S) between our result and the experimental and theoretical results in the literatures 19 and 20. The discrepancy between our results and previous results would be related to the difference of the nanostructure in Pt-Au alloys related to the scattering from film surfaces and grain boundaries and the degree of phase separation in Pt-Au alloy systems.