Rashba spin-orbit coupling and spin relaxation in silicon quantum wells

TL;DR

This paper calculates spin relaxation times in silicon quantum wells due to Rashba spin-orbit coupling, providing insights into optimizing device design for spin-based quantum computing and spintronics.

Contribution

It applies the D'yakonov-Perel' theory to silicon 2DEGs, estimating Rashba coupling and spin relaxation times for various conditions, aligning with experimental data.

Findings

Agreement with existing experimental data on relaxation times

Identification of device parameters affecting spin relaxation

Suggestions for increasing spin relaxation times through design

Abstract

Silicon is a leading candidate material for spin-based devices, and two-dimensional electron gases (2DEGs) formed in silicon heterostructures have been proposed for both spin transport and quantum dot quantum computing applications. The key parameter for these applications is the spin relaxation time. Here we apply the theory of D'yakonov and Perel' (DP) to calculate the electron spin resonance linewidth of a silicon 2DEG due to structural inversion asymmetry for arbitrary static magnetic field direction at low temperatures. We estimate the Rashba spin-orbit coupling coefficient in silicon quantum wells and find the $T_{1}$ and $T_{2}$ times of the spins from this mechanism as a function of momentum scattering time, magnetic field, and device-specific parameters. We obtain agreement with existing data for the angular dependence of the relaxation times and show that the magnitudes are consistent with the DP mechanism. We suggest how to increase the relaxation times by appropriate device design.