Temperature and Electron Density Dependence of Spin Relaxation in GaAs/AlGaAs Quantum Well

TL;DR

This study investigates how temperature and electron density affect spin relaxation times in GaAs/AlGaAs quantum wells, highlighting the influence of structural symmetry and Coulomb scattering mechanisms.

Contribution

It provides experimental evidence linking quantum well symmetry and Rashba spin-orbit coupling to spin relaxation, supported by microscopic kinetic spin Bloch equation theory.

Findings

Symmetric quantum wells have longer spin relaxation times.

D'yakonov-Perel' mechanism dominates spin relaxation.

Spin relaxation time varies non-monotonically with temperature and density.

Abstract

Temperature and carrier density dependent spin dynamics for GaAs/AlGaAs quantum wells (QWs) with different structural symmetry has been studied by using time-resolved Kerr rotation technique. The spin relaxation time is measured to be much longer for the symmetrically-designed GaAs quantum well comparing with the asymmetrical one, indicating the strong influence of Rashba spin-orbit coupling on spin relaxation. D'yakonov-Perel' (DP) mechanism has been revealed to be the dominant contribution for spin relaxation in GaAs/AlGaAs QWs. The spin relaxation time exhibits non-monotonic dependent behavior on both temperature and photo-excited carrier density, revealing the important role of non-monotonic temperature and density dependence of electron-electron Coulomb scattering. Our experimental observations demonstrate good agreement with recently developed spin relaxation theory based on microscopic kinetic spin Bloch equation approach.