Spin-orbit fields in asymmetric (001) quantum wells

TL;DR

This study measures electron spin properties in asymmetric quantum wells to determine spin-orbit coupling coefficients, revealing that Rashba effects can be negligible despite structural asymmetry due to potential isomorphism.

Contribution

It provides a novel method to extract Rashba and Dresselhaus coefficients from combined measurements of g-factor and spin relaxation rate in quantum wells.

Findings

Rashba coefficient can be negligible despite structural asymmetry

The in-plane g-factor and spin relaxation rate measurements reveal spin-orbit coupling strengths

Potential asymmetry from alloy variations does not necessarily induce Rashba effects

Abstract

We measure simultaneously the in-plane electron g-factor and spin relaxation rate in a series of undoped inversion-asymmetric (001)-oriented GaAs/AlGaAs quantum wells by spin-quantum beat spectroscopy. In combination the two quantities reveal the absolute values of both the Rashba and the Dresselhaus coefficients and prove that the Rashba coefficient can be negligibly small despite huge conduction band potential gradients which break the inversion symmetry. The negligible Rashba coefficient is a consequence of the 'isomorphism' of conduction and valence band potentials in quantum systems where the asymmetry is solely produced by alloy variations.