Confinement-enhanced spin relaxation for electron ensembles in large quantum dots

TL;DR

This study numerically investigates how confinement in large quantum dots unexpectedly enhances spin relaxation of electron ensembles, contrasting with previous beliefs that confinement suppresses relaxation.

Contribution

It reveals that in micron-scale quantum dots, confinement can significantly increase spin relaxation, especially when system size is comparable to the spin precession length.

Findings

Confinement in large quantum dots enhances spin relaxation.

Relaxation is increased when system size matches the spin precession length.

Contradicts previous understanding that confinement reduces spin relaxation.

Abstract

We present a numerical study of spin relaxation in a semiclassical electron ensemble in a large ballistic quantum dot. The dot is defined in a GaAs/AlGaAs heterojunction system with a two-dimensional electron gas, and relaxation occurs due to Dresselhaus and Rashba spin orbit interaction. We find that confinement in a micronscale dot can result in strongly enhanced relaxation with respect to a free two-dimensional electron ensemble, contrary to the established result that strong confinement or frequent momentum scattering reduces relaxation. This effect occurs when the size of the system is on the order of the spin precession length, but smaller than the mean free path.