Spatiotemporal spin fluctuations caused by spin-orbit-coupled Brownian motion

TL;DR

This paper develops a theory describing how thermal spin density fluctuations in a 2D electron gas are correlated in space and time due to Brownian motion and spin-orbit coupling, enabling parameter extraction from measurements.

Contribution

It introduces a comprehensive theoretical framework for spatiotemporal spin fluctuations in 2D electron gases considering various spin-orbit interactions.

Findings

Correlation functions differ for ballistic and diffusive regimes.

Spin fluctuations reveal spin-orbit coupling parameters.

Measurement can probe spin transport near thermal equilibrium.

Abstract

We develop a theory of thermal fluctuations of spin density emerging in a two-dimensional electron gas. The spin fluctuations probed at spatially separated spots of the sample are correlated due to Brownian motion of electrons and spin-obit coupling. We calculate the spatiotemporal correlation functions of the spin density for both ballistic and diffusive transport of electrons and analyze them for different types of spin-orbit interaction including the isotropic Rashba model and persistent spin helix regime. The measurement of spatial spin fluctuations provides direct access to the parameters of spin-orbit coupling and spin transport in conditions close to the thermal equilibrium.