Hole spin relaxation in intrinsic and $p$-type bulk GaAs

TL;DR

This study uses a microscopic kinetic spin Bloch equation approach to analyze hole spin relaxation in intrinsic and p-type bulk GaAs, highlighting the importance of intraband coherence, hole-optical-phonon interactions, and screening effects, with results aligning with experimental data.

Contribution

It provides a comprehensive microscopic analysis of hole spin relaxation mechanisms, including the effects of intraband coherence and screening, which were not fully considered in previous studies.

Findings

Elliott-Yafet mechanism dominates in intrinsic GaAs at room temperature.

Hole spin relaxation time exhibits a valley at low temperature due to hole-electron scattering.

A peak in spin relaxation time versus hole density is predicted in p-type GaAs at low temperature.

Abstract

We investigate hole spin relaxation in intrinsic and $p$-type bulk GaAs from a fully microscopic kinetic spin Bloch equation approach. In contrast to the previous study on hole spin dynamics, we explicitly include the intraband coherence and the nonpolar hole-optical-phonon interaction, both of which are demonstrated to be of great importance to the hole spin relaxation. The relative contributions of the D'yakonov-Perel' and Elliott-Yafet mechanisms on hole spin relaxation are also analyzed. In our calculation, the screening constant, playing an important role in the hole spin relaxation, is treated with the random phase approximation. In intrinsic GaAs, our result shows good agreement with the experiment data at room temperature, where the hole spin relaxation is demonstrated to be dominated by the Elliott-Yafet mechanism. We also find that the hole spin relaxation strongly depends on the temperature and predict a valley in the density dependence of the hole spin relaxation time at low temperature due to the hole-electron scattering. In $p$-type GaAs, we predict a peak in the spin relaxation time against the hole density at low temperature, which originates from the distinct behaviors of the screening in the degenerate and nondegenerate regimes. The competition between the screening and the momentum exchange during scattering events can also lead to a valley in the density dependence of the hole spin relaxation time in the low density regime. At high temperature, the effect of the screening is suppressed due to the small screening constant. Moreover, we predict a nonmonotonic dependence of the hole spin relaxation time on temperature associated with the screening together with the hole-phonon scattering. Finally, we find that the D'yakonov-Perel' mechanism can markedly contribute to the .... (omitted due to the limit of space)