Highly efficient spin current generation by the spin Hall effect in Au$_{1-x}$Pt$_x$

TL;DR

This paper demonstrates that the Au0.25Pt0.75 alloy is an exceptionally efficient spin current generator via the spin Hall effect, surpassing other heavy metals and topological insulators in energy efficiency and potential spintronic applications.

Contribution

The study reports the discovery of highly efficient spin current generation in Au0.25Pt0.75 alloy, with a giant spin Hall ratio and conductivity, establishing it as a milestone material for spintronics.

Findings

Giant internal spin Hall ratio of > 0.58

Spin Hall conductivity > 7.0x10^5 ohm^-1 m^-1

Low resistivity of ~ 83 uOhm cm

Abstract

We report very efficient spin current generation by the spin Hall effect in the alloy Au0.25Pt0.75, which, as determined by two different direct spin-orbit torque measurements, exhibits a giant internal spin Hall ratio of > 0.58 (anti-damping spin-orbit torque efficiency of ~ 0.35 in bilayers with Co), a relatively low resistivity of ~ 83 uOhm cm, an exceptionally large spin Hall conductivity of > 7.0x10^5 ohm^-1 m^-1, and a spin diffusion length of 1.7 nm. This work establishes Au0.25Pt0.75 as a milestone spin current generator that provides greater energy efficiency than that yet obtained with other heavy metals or with the topological insulators Bi2Se3 and (Bi,Se)2Te3. Our findings should advance spin-orbit torque-based fundamental research and benefit the development of new fast, efficient spin-orbit torque-driven magnetic memories, skyrmion and chiral domain wall devices, and microwave and terahertz emitters.