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

TL;DR

This study systematically investigates the spin Hall effect in platinum across various conductivities, revealing a crossover between different scaling regimes and providing insights into optimizing spin Hall angles for spintronic applications.

Contribution

It is the first to demonstrate the crossover between dirty and superclean regimes of the spin Hall effect in Pt by tuning conductivity, aligning experimental results with theoretical predictions.

Findings

Linear relation between spin diffusion length and conductivity.

Single intrinsic spin Hall conductivity of approximately 1600 Ω^{-1}cm^{-1}.

Identification of the crossover between scaling regimes.

Abstract

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 the spin diffusion length and the conductivity, evidencing that the spin relaxation in Pt is governed by the Elliott-Yafet mechanism. We find a single intrinsic spin Hall conductivity ($\sigma_{SH}^{int}=1600\pm150\: \Omega^{-1}cm^{-1}$) for Pt in the full range studied which is in good agreement with theory. For the first time we have obtained the crossover between the moderately dirty and the superclean scaling regimes of the spin Hall effect by tuning the conductivity. This is equivalent to that obtained for the anomalous Hall effect. Our results explain the spread of the spin Hall angle values in the literature and find a route to maximize this important parameter.