Polarization-induced Rashba spin-orbit coupling in structurally symmetric III-Nitride quantum wells

TL;DR

This paper investigates how internal electric fields and structural asymmetries in Ga- and N-face InGaN quantum wells influence Rashba spin-orbit coupling and spin-splitting, revealing sign differences and magnitude comparable to experimental observations.

Contribution

It demonstrates that the sign of SIA spin-orbit coupling depends on internal electric fields, with the effective linear coupling coefficient always positive due to Dresselhaus contribution.

Findings

Sign of SIA spin-orbit coupling varies with internal electric field.

Effective linear coupling coefficient remains positive.

Spin-splitting magnitude aligns with experimental data.

Abstract

The effective linear coupling coefficient and the total spin-splitting are calculated in Ga- and N- face InGaN quantum wells. Alloy content, geometry, and gate voltage affect an internal field and an electron density distribution in the growth direction that has direct effect on a spin-splitting. The sign of structural inversion asymmetry (SIA) spin-orbit coupling coefficient depends on an internal electric field in the well that results in different signs for Ga-face and N-face III-Nitride structures. The effective linear coupling coefficient is always positive because of the Dresselhaus-type contribution that is a major one in quantum wells under consideration. The magnitude of the spin-splitting is comparable with that experimentally observed in III-Nitrides and III-V zinc-blende structures.