Spin-orbit Hanle effect in high-mobility quantum wells

TL;DR

This paper investigates how the Hanle effect in quantum wells varies with carrier mobility, revealing a nonmonotonic behavior in high-mobility structures and proposing a method to measure spin-orbit fields.

Contribution

It demonstrates the dependence of the Hanle curve shape on mobility and introduces a way to measure spin-orbit fields using the Hanle maximum position.

Findings

Hanle curve is Lorentzian in low-mobility structures.

High-mobility quantum wells show nonmonotonic spin polarization dependence.

Maximum of the Hanle curve can measure spin-orbit Rashba/Dresselhaus fields.

Abstract

We study the depolarization of optically oriented electrons in quantum wells subjected to an in-plane magnetic field and show that the Hanle curve drastically depends on the carrier mobility. In low-mobility structures, the Hanle curve is described by a Lorentzian with the width determined by the effective g-factor and the spin lifetime. In contrast, the magnetic field dependence of spin polarization in high-mobility quantum wells is nonmonotonic: The spin polarization rises with the magnetic field induction at small fields, reaches maximum and then decreases. We show that the position of the Hanle curve maximum can be used to directly measure the spin-orbit Rashba/Dresselhaus magnetic field.