Suppression of Dyakonov-Perel Spin Relaxation in high mobility n-GaAs

TL;DR

This study reveals a significant suppression of Dyakonov-Perel spin relaxation in high mobility n-GaAs, challenging existing theories and suggesting new avenues for spin memory engineering at high temperatures.

Contribution

It demonstrates an unexpected suppression of spin relaxation in n-GaAs, with a novel interpretation of spin-orbit field dynamics differing from traditional models.

Findings

Spin relaxation rate saturates at 30 times lower than predicted.

Weak dependence of spin relaxation on mobility.

Correlation time of spin-orbit field is shorter and independent of momentum relaxation time.

Abstract

We report a large and unexpected suppression of the free electron spin relaxation in lightly-doped n-GaAs bulk crystals. The spin relaxation rate shows weak mobility dependence and saturates at a level 30 times less then that predicted by the Dyakonov-Perel theory. The dynamics of the spin-orbit field differs substantially from the usual scheme: although all the experimental data can be self-consistently interpreted as a precessional spin relaxation induced by a random spin-orbit field, the correlation time of this random field, surprisingly, is much shorter than, and is independent of, the momentum relaxation time determined from transport measurements. Understanding of this phenomenon could lead to high temperature engineering of the electron spin memory.