Spin-orbit induced hole spin relaxation in InAs and GaAs quantum dots

TL;DR

This paper investigates how spin-orbit interactions influence hole spin relaxation in InAs and GaAs quantum dots, revealing the roles of hh-lh mixing and BIA, and their dependence on quantum dot geometry and experimental conditions.

Contribution

It provides a comprehensive 3D analysis of valence band spin-orbit effects, clarifying their relative importance in different quantum dot configurations and resolving previous theoretical discrepancies.

Findings

BIA dominates in gated quantum dots.

Hole spin relaxation shows non-monotonic dependence on QD geometry.

Results align with experimental observations.

Abstract

We study the effect of valence band spin-orbit interactions on the acoustic phonon assisted spin relaxation of holes confined in quantum dots. Heavy hole-light hole (hh-lh) mixing and all the spin-orbit terms arising from zinc-blende bulk inversion asymmetry (BIA) are considered on equal footing in a fully 3D Hamiltonian. We show that hh-lh mixing and BIA have comparable contributions to the hole spin relaxation in self-assembled QDs, but BIA becomes dominant in gated QDs. The dependence of the hole spin relaxation on the QD geometry and spin splitting energy is drastically different from that of electrons, with a non-monotonic behavior which results from the interplay between SOI terms. Our results reconcile contradictory predictions of previous theoretical works and are consistent with experiments.