Non-diffusive spin dynamics in a two-dimensional electron gas

TL;DR

This paper investigates spin dynamics in a 2D electron gas in GaAs/GaAlAs quantum wells, revealing that spin polarization lifetime peaks at nonzero wavevector, aligning with theories including spin-orbit coupling effects.

Contribution

It provides experimental measurements of spin relaxation rates across wavevectors, confirming theoretical predictions about non-diffusive spin behavior in spin-orbit coupled systems.

Findings

Spin polarization lifetime is maximal at nonzero wavevector.

Experimental results agree with recent theories including spin-orbit coupling.

Optical techniques like transient spin-grating spectroscopy effectively probe spin dynamics.

Abstract

We describe measurements of spin dynamics in the two-dimensional electron gas in GaAs/GaAlAs quantum wells. Optical techniques, including transient spin-grating spectroscopy, are used to probe the relaxation rates of spin polarization waves in the wavevector range from zero to $6\times 10^4$ cm$^{-1}$. We find that the spin polarization lifetime is maximal at nonzero wavevector, in contrast with expectation based on ordinary spin diffusion, but in quantitative agreement with recent theories that treat diffusion in the presence of spin-orbit coupling.