Nonlinear Rashba Model and Spin Relaxation in Quantum Wells

TL;DR

This paper introduces a nonlinear Rashba model for quantum wells, revealing significant deviations from the linear model, especially in narrow-gap materials, and predicts new behaviors in spin relaxation rates and resonance peaks.

Contribution

A nonlinear Rashba model is proposed that aligns well with numerical results and captures complex spin relaxation phenomena in quantum wells.

Findings

Nonlinear Rashba spin splitting is significant in narrow-gap materials.

Pronounced suppression of spin relaxation rate at high electron densities.

Non-monotonic dependence of spin lifetime resonance on electron density.

Abstract

We find that the Rashba spin splitting is intrinsically a nonlinear function of the momentum, and the linear Rasha model may overestimate it significantly, especially in narrow-gap materials. A nonlinear Rashba model is proposed, which is in good agreement with the numerical results from the eight-band kp theory. Using this model, we find pronounced suppression of the D'yakonov-Perel' spin relaxation rate at large electron densities, and a non-monotonic dependence of the resonance peak position of electron spin lifetime on the electron density in [111]-oriented quantum wells, both in qualitative disagreement with the predictions of the linear Rashba model.