Electron g-Factor Anisotropy in Symmetric (110)-oriented GaAs Quantum Wells

TL;DR

This study reveals that symmetric (110)-oriented GaAs quantum wells exhibit an in-plane electron g-factor anisotropy, which is a higher order effect independent of common asymmetries, and can be accurately modeled by advanced band theory.

Contribution

It demonstrates that symmetric quantum wells can have anisotropic g-factors due to higher order effects, expanding understanding of spin properties in symmetric systems.

Findings

g-factor anisotropy exists in symmetric (110) GaAs quantum wells

14x14 band k.p theory accurately models the anisotropy

Fourth order perturbation theory provides analytical insight

Abstract

We demonstrate by spin quantum beat spectroscopy that in undoped symmetric (110)-oriented GaAs/AlGaAs single quantum wells even a symmetric spatial envelope wavefunction gives rise to an asymmetric in-plane electron Land\'e-g-factor. The anisotropy is neither a direct consequence of the asymmetric in-plane Dresselhaus splitting nor of the asymmetric Zeeman splitting of the hole bands but is a pure higher order effect that exists as well for diamond type lattices. The measurements for various well widths are very well described within 14 x 14 band k.p theory and illustrate that the electron spin is an excellent meter variable to map out the internal -otherwise hidden- symmetries in two dimensional systems. Fourth order perturbation theory yields an analytical expression for the strength of the g-factor anisotropy, providing a qualitative understanding of the observed effects.