Observation of Spin Relaxation Anisotropy in Semiconductor Quantum Wells

TL;DR

This study measures spin relaxation times in asymmetrical AlGaAs quantum wells, revealing anisotropy linked to spin-orbit coupling, with Rashba effects being significantly stronger than Dresselhaus effects.

Contribution

It provides the first detailed measurement of spin relaxation anisotropy and quantifies the relative strengths of Rashba and Dresselhaus spin-orbit interactions.

Findings

Three distinct spin relaxation times demonstrate anisotropy.

Rashba spin-orbit splitting is approximately four times stronger than Dresselhaus.

Spin relaxation is influenced by the interplay of spin-orbit coupling mechanisms.

Abstract

Spin relaxation of two-dimensional electrons in asymmetrical (001) AlGaAs quantum wells are measured by means of Hanle effect. Three different spin relaxation times for spins oriented along [110], [1-10] and [001] crystallographic directions are extracted demonstrating anisotropy of D'yakonov-Perel' spin relaxation mechanism. The relative strengths of Rashba and Dresselhaus terms describing the spin-orbit coupling in semiconductor quantum well structures. It is shown that the Rashba spin-orbit splitting is about four times stronger than the Dresselhaus splitting in the studied structure.