Intersubband spin-orbit coupling and spin splitting in symmetric quantum wells

TL;DR

This paper investigates intersubband spin-orbit coupling in symmetric quantum wells, finding that its contribution to spin splitting is negligible in typical III-V structures, despite its theoretical significance.

Contribution

It introduces and analyzes an intersubband spin-orbit term in symmetric quantum wells, showing its negligible effect on spin splitting in common materials.

Findings

Intersubband spin-orbit coupling exists in symmetric quantum wells.

The resulting spin splitting is negligible for typical III-V quantum wells.

The intersubband term's strength is comparable to Rashba coupling but remains insignificant in practice.

Abstract

In semiconductors with inversion asymmetry, spin-orbit coupling gives rise to the well-known Dresselhaus and Rashba effects. If one considers quantum wells with two or more conduction subbands, an additional, intersubband-induced spin-orbit term appears whose strength is comparable to the Rashba coupling, and which remains finite for symmetric structures. We show that the conduction band spin splitting due to this intersubband spin-orbit coupling term is negligible for typical III-V quantum wells.