Extrinsic Spin Hall Effect from Anisotropic Rashba Spin-Orbit Coupling in Graphene

TL;DR

This paper investigates how anisotropic Rashba spin-orbit coupling influences the extrinsic spin Hall effect in graphene, revealing that anisotropy significantly alters the spin Hall angle's dependence on carrier concentration.

Contribution

It introduces a generalized anisotropic Rashba coupling model that accounts for symmetry breaking in graphene and demonstrates its impact on the spin Hall effect.

Findings

Rashba anisotropy modifies the spin Hall angle dependence on carrier concentration.

The model captures skew scattering mechanisms induced by adatom clusters.

Anisotropic Rashba coupling can enhance or suppress the spin Hall effect.

Abstract

We study the effect of anisotropy of the Rashba coupling on the extrinsic spin Hall effect due to spin-orbit active adatoms on graphene. In addition to the intrinsic spin-orbit coupling, a generalized anisotropic Rashba coupling arising from the breakdown of both mirror and hexagonal symmetries of pristine graphene is considered. We find that Rashba anisotropy can strongly modify the dependence of the spin Hall angle on carrier concentration. Our model provides a simple and general description of the skew scattering mechanism due to the spin-orbit coupling that is induced by proximity to large adatom clusters.