Giant spin-orbit splitting in inverted InAs/GaSb double quantum wells

TL;DR

This paper reports the observation of giant spin-orbit splitting in inverted InAs/GaSb quantum wells, leading to full spin polarization and exotic quantum Hall phenomena, advancing understanding of spin-related effects in semiconductor heterostructures.

Contribution

The study demonstrates for the first time the large spin-orbit splitting and full spin polarization in inverted InAs/GaSb quantum wells, revealing new quantum transport phenomena.

Findings

Giant spin-orbit splitting exceeds the hybridization gap.

Full spin polarization enables quantum Hall plateaus in $e^2/h$ steps.

Observation of a non-trivial Berry phase.

Abstract

Transport measurements in inverted InAs/GaSb quantum wells reveal a giant spin-orbit splitting of the energy bands close to the hybridization gap. The splitting results from the interplay of electron-hole mixing and spin-orbit coupling, and can exceed the hybridization gap. We experimentally investigate the band splitting as a function of top gate voltage for both electron-like and hole-like states. Unlike conventional, noninverted two-dimensional electron gases, the Fermi energy in InAs/GaSb can cross a single spin-resolved band, resulting in full spin-orbit polarization. In the fully polarized regime we observe exotic transport phenomena such as quantum Hall plateaus evolving in $e^2/h$ steps and a non-trivial Berry phase.