Influence of magnetic quantum confined Stark effect on the spin lifetime of indirect excitons

TL;DR

This paper investigates how the magnetic quantum confined Stark effect influences the spin lifetime of indirect excitons in coupled quantum wells, revealing non-intuitive magnetic field dependence of spin relaxation times.

Contribution

It demonstrates the non-monotonic behavior of exciton spin lifetime under magnetic fields, linking it to the magnetic quantum confined Stark effect in CQWs.

Findings

Spin lifetime increases at low magnetic fields

Saturation and decrease of spin lifetime at higher fields

Magnetic field suppresses exciton spin coherence due to g-factor broadening

Abstract

We report on the unusual and counter-intuitive behaviour of spin lifetime of excitons in coupled semiconductor quantum wells (CQWs) in the presence of in-plane magnetic field. Instead of conventional acceleration of spin relaxation due to the Larmor precession of electron and hole spins we observe a strong increase of the spin relaxation time at low magnetic fields followed by saturation and decrease at higher fields. We argue that this non-monotonic spin relaxation dynamics is a fingerprint of the magnetic quantum confined Stark effect. In the presence of electric field along the CQW growth axis, an applied magnetic field efficiently suppresses the exciton spin coherence, due to inhomogeneous broadening of the $g$-factor distribution.