Weak Localization, Spin Relaxation, and Spin-Diffusion: The Crossover Between Weak and Strong Rashba Coupling Limits

TL;DR

This paper investigates how Rashba spin-orbit coupling influences spin relaxation and diffusion in a 2D electron gas, revealing a non-monotonic WL-WAL crossover driven by spin channel mixing, with implications for oxide interface transport.

Contribution

It provides a detailed analysis of the WL-WAL crossover in the intermediate Rashba coupling regime, highlighting the role of spin channel mixing in spin transport phenomena.

Findings

The WL-WAL crossover is non-monotonic when spin channel mixing is significant.

Spin-orbit coupling can switch quantum interference correction from negative to positive.

Results help interpret transport experiments at oxide interfaces.

Abstract

Disorder scattering and spin-orbit coupling are together responsible for the diffusion and relaxation of spin-density in time-reversal invariant systems. We study spin-relaxation and diffusion in a two-dimensional electron gas with Rashba spin-orbit coupling and spin-independent disorder, focusing on the role of Rashba spin-orbit coupling in transport. Spin-orbit coupling contributes to spin relaxation, transforming the quantum interference contribution to conductivity from a negative weak localization (WL) correction to a positive weak anti-localization (WAL) correction. The importance of spin channel mixing in transport is largest in the regime where the Bloch state energy uncertainty $\hbar/\tau$ and the Rashba spin-orbit splitting $\Delta_\mathrm{SO}$ are comparable. We find that as a consequence of this spin channel mixing, the WL-WAL crossover is non-monotonic in this intermediate regime, and use our results to address recent experimental studies of transport at two-dimensional oxide interfaces.