Spin-orbit anisotropy measured using ballistic spin resonance

TL;DR

This paper investigates how spin relaxation varies with channel orientation in a two-dimensional electron gas, revealing significant anisotropy due to ballistic spin resonance mediated by spin-orbit interaction.

Contribution

It provides a direct measurement of spin-orbit anisotropy by comparing spin relaxation in channels oriented along different crystal axes in GaAs.

Findings

Stronger spin relaxation observed in [110] channels compared to [-110].

Spin-orbit anisotropy linked to interference between structural and bulk inversion asymmetries.

Electrical measurements effectively reveal differences in spin relaxation based on channel orientation.

Abstract

Spin relaxation can be greatly enhanced in narrow channels of two-dimensional electron gas due to ballistic spin resonance, which is mediated by spin-orbit interaction for trajectories that bounce rapidly between channel walls. The channel orientation determines which momenta affect the relaxation process, so comparing relaxation for two orientations provides a direct determination of spin-orbit anisotropy. Electrical measurements of pure spin currents are shown to reveal an order of magnitude stronger relaxation for channels fabricated along the [110] crystal axis in a GaAs electron gas compared to [-110] channels, believed to result from interference between structural and bulk inversion asymmetries.