Large Bychkov-Rashba spin-orbit coupling in high-mobility GaN/AlGaN heterostructures

TL;DR

This study demonstrates strong Bychkov-Rashba spin-orbit coupling in high-mobility GaN/AlGaN heterostructures through magnetoconductivity measurements, providing new insights into spin-related phenomena in wide bandgap semiconductors.

Contribution

The paper provides the first detailed measurement and analysis of Rashba spin-orbit coupling in GaN/AlGaN heterostructures, including a closed-form expression for magnetoconductivity and precise coupling constants.

Findings

Rashba spin-orbit coupling constant $eta_{so} \,\sim\, 6\times10^{-13}$ eVm

Conduction band spin-orbit splitting energy $\,\sim\, 0.3$ meV

Pronounced anti-localization minima indicating strong spin-orbit effects

Abstract

We present low temperature magnetoconductivity measurements of a density-tunable and high mobility two-dimensional electron gas confined in the wide bandgap GaN/AlGaN system. We observed pronounced anti-localization minima in the low-field conductivity, indicating the presence of strong spin-orbit coupling. Density dependent measurements of magnetoconductivity indicate that the coupling is mainly due to the Bychkov-Rashba mechanism. In addition, we have derived a closed-form expression for the magnetoconductivity, allowing us to extract reliable transport parameters for our devices. The Rashba spin-orbit coupling constant is $\alpha_{so}$ $\sim$ 6$\times$ 10$^{-13}$eVm, while the conduction band spin-orbit splitting energy amounts to $\Delta_{so}$ $\sim$ 0.3meV at n$_e$=1$\times10^{16}$m$^{-2}$.