Tuning Rashba spin-orbit coupling in homogeneous semiconductor nanowires

TL;DR

This paper uses $oldsymbol{k}oldsymbol{ullet}oldsymbol{p}$ theory to estimate and analyze gate-controlled Rashba spin-orbit coupling in semiconductor nanowires, revealing non-linear electric field effects and comparing with experimental data.

Contribution

It provides a detailed theoretical analysis of Rashba SOC in nanowires, highlighting non-linear effects and reconciling discrepancies with experimental measurements.

Findings

Good agreement with some experimental SOC values

SOC exhibits non-linear electric field dependence at high carrier densities

Discrepancies with larger reported SOC values are discussed

Abstract

We use $\vec{k}\cdot\vec{p}$ theory to estimate the Rashba spin-orbit coupling (SOC) in large semiconductor nanowires. We specifically investigate GaAs- and InSb-based devices with different gate configurations to control symmetry and localization of the electron charge density. We explore gate-controlled SOC for wires of different size and doping, and we show that in high carrier density SOC has a non-linear electric field susceptibility, due to large reshaping of the quantum states. We analyze recent experiments with InSb nanowires in light of our calculations. Good agreement is found with SOC coefficients reported in Phys. Rev.B 91, 201413(R) (2015), but not with the much larger values reported in Nat Commun., 8, 478 (2017). We discuss possible origins of this discrepancy.