Tuning the spin Hall effect of Pt from the moderately dirty to the superclean regime

Edurne Sagasta, Yasutomo Omori, Miren Isasa, Martin Gradhand, Luis E. Hueso, Yasuhiro Niimi, YoshiChika Otani, Fèlix Casanova

Published 2016-03-16Version 1

We systematically measure and analyze the spin diffusion length and the spin Hall effect in Pt with a wide range of conductivities using the spin absorption method in lateral spin valve devices. We observe a linear relation between spin diffusion length and conductivity, evidencing that spin relaxation in Pt is governed by the Elliott-Yafet mechanism. We find a single intrinsic spin Hall conductivity ($\sigma_{SH}^{int}=1540\pm100\: \Omega^{-1}cm^{-1}$) for Pt in the full range studied which is in good agreement with theory. By tuning the conductivity, we have obtained for the first time the crossover between the moderately dirty and the superclean scaling regimes of the spin Hall effect, equivalent to that obtained for the anomalous Hall effect. Our results explain the dispersion of spin Hall angle values in the literature and find a route to maximize this important parameter.