Demonstration of Rashba spin splitting in GaN-based heterostructures

TL;DR

This paper reports the experimental observation of Rashba spin splitting in GaN-based heterostructures through the circular photogalvanic effect, indicating significant spin-orbit interaction due to interface asymmetry.

Contribution

First demonstration of Rashba spin splitting in GaN heterostructures using CPGE, highlighting the role of built-in interface asymmetry.

Findings

CPGE observed in GaN quantum wells

Photocurrent sign reversal with radiation helicity

Evidence of sizeable Rashba spin splitting

Abstract

The circular photogalvanic effect (CPGE), induced by infrared radiation, has been observed in (0001)-oriented GaN quantum well (QW) structures. The photocurrent changes sign upon reversing the radiation helicity demonstrating the existence of spin-splitting of the conduction band in k-space in this type of materials. The observation suggests the presence of a sizeable Rashba type of spin-splitting, caused by the built-in asymmetry at the AlGaN/GaN interface.