Control of Spin Relaxation Anisotropy by Spin-Orbit-Coupled Diffusive Spin Motion

TL;DR

This paper demonstrates that spin relaxation anisotropy in a GaAs two-dimensional electron gas can be controlled by diffusive electron motion, revealing nonlinear spin precession behavior near spin-orbit and magnetic field cancellation.

Contribution

It uncovers how diffusive electron motion influences spin relaxation anisotropy, enabling control over spin dynamics through diffusion in spin-orbit coupled systems.

Findings

Spin precession frequency depends nonlinearly on diffusion velocity near cancellation points.

Electron velocity perpendicular to diffusion enhances spin relaxation anisotropy.

Spin relaxation anisotropy can be manipulated via diffusive electron motion.

Abstract

Spatiotemporal spin dynamics under spin-orbit interaction is investigated in a (001) GaAs two-dimensional electron gas using magneto-optical Kerr rotation microscopy. Spin polarized electrons are diffused away from the excited position, resulting in spin precession because of the diffusion-induced spin-orbit field. Near the cancellation between spin-orbit field and external magnetic field, the induced spin precession frequency depends nonlinearly on the diffusion velocity, which is unexpected from the conventional linear relation between the spin-orbit field and the electron velocity.This behavior originates from an enhancement of the spin relaxation anisotropy by the electron velocity perpendicular to the diffused direction. We demonstrate that the spin relaxation anisotropy, which has been regarded as a material constant, can be controlled via diffusive electron motion.