Density dependence of spin relaxation in GaAs quantum well at room temperature

TL;DR

This study investigates how electron spin relaxation times in GaAs quantum wells vary with carrier density at room temperature, revealing a non-monotonic behavior explained by spin-orbit coupling mechanisms and supported by microscopic calculations.

Contribution

It provides experimental and theoretical insights into the density-dependent spin relaxation in GaAs quantum wells, incorporating both D'yakonov-Perel' and Bir-Aronov-Pikus mechanisms.

Findings

Spin relaxation time increases then decreases with density.

Experimental results agree with theoretical predictions.

Microscopic calculations accurately reproduce the density dependence.

Abstract

Carrier density dependence of electron spin relaxation in an intrinsic GaAs quantum well is investigated at room temperature using time-resolved circularly polarized pump-probe spectroscopy. It is revealed that the spin relaxation time first increases with density in the relatively low density regime where the linear D'yakonov-Perel' spin-orbit coupling terms are dominant, and then tends to decrease when the density is large and the cubic D'yakonov-Perel' spin-orbit coupling terms become important. These features are in good agreement with theoritical predictions by L\"u {\em et al.} [Phys. Rev. B {\bf 73}, 125314 (2006)]. A fully microscopic calculation based on numerically solving the kinetic spin Bloch equations with both the D'yakonov-Perel' and the Bir-Aronov-Pikus mechanisms included, reproduces the density dependence of spin relaxation very well.