Hole spin dynamics and hole $g$ factor anisotropy in coupled quantum well systems

TL;DR

This study investigates the anisotropic behavior of hole spins and their $g$ factors in coupled GaAs quantum wells, revealing how crystal symmetry influences spin dynamics and providing insights for spintronic applications.

Contribution

It provides the first direct measurement and theoretical analysis of hole $g$ factor anisotropy in coupled quantum wells with different crystallographic orientations.

Findings

Large in-plane anisotropy of hole $g$ factor observed in low-symmetry orientations

Crystal symmetry affects hole spin dephasing times

Theoretical calculations agree with experimental measurements

Abstract

Due to its p-like character, the valence band in GaAs-based heterostructures offers rich and complex spin-dependent phenomena. One manifestation is the large anisotropy of Zeeman spin splitting. Using undoped, coupled quantum wells (QWs), we examine this anisotropy by comparing the hole spin dynamics for high- and low-symmetry crystallographic orientations of the QWs. We directly measure the hole $g$ factor via time-resolved Kerr rotation, and for the low-symmetry crystallographic orientations (110) and (113a), we observe a large in-plane anisotropy of the hole $g$ factor, in good agreement with our theoretical calculations. Using resonant spin amplification, we also observe an anisotropy of the hole spin dephasing in the (110)-grown structure, indicating that crystal symmetry may be used to control hole spin dynamics.