Spin relaxation in quantum dots with random spin-orbit coupling

TL;DR

This paper studies how random variations in spin-orbit coupling within quantum dots limit the effectiveness of external bias in reducing spin relaxation rates, revealing persistent spin-flip processes due to nanoscale randomness.

Contribution

It introduces the impact of nanoscale randomness in spin-orbit coupling on spin relaxation in quantum dots, highlighting limitations of bias tuning.

Findings

Spin relaxation rate remains significant despite bias compensation.

Random spin-orbit coupling cannot be fully eliminated by external bias.

Spin-flip transitions are influenced by nanoscale randomness.

Abstract

We investigate the longitudinal spin relaxation arising due to spin-flip transitions accompanied by phonon emission in quantum dots where the strength of the Rashba spin-orbit coupling is a random function of the lateral (in-plane) coordinate on the spatial nanoscale. In this case the Rashba contribution to the spin-orbit coupling cannot be completely removed by applying a uniform external bias across the quantum dot plane. Due to the remnant random contribution, the spin relaxation rate cannot be decreased by more than two orders of magnitude even when the external bias fully compensates the regular part of the spin-orbit coupling.