Experimental Signatures of the Inverted Phase in InAs/GaSb Coupled Quantum Wells

TL;DR

This study investigates the unique electronic properties of InAs/GaSb coupled quantum wells, revealing signatures of an inverted topological phase through transport measurements and magnetic field responses.

Contribution

It provides experimental evidence of the inverted phase in InAs/GaSb quantum wells, highlighting the effects of spin-orbit interaction and magnetic fields on their topological properties.

Findings

Suppression of resistance peak at charge neutrality point in magnetic field

Observation of an unconventional Landau level spectrum

Evidence of a topological hybridization gap

Abstract

Transport measurements are performed on InAs/GaSb double quantum wells at zero and finite magnetic fields applied parallel and perpendicular to the quantum wells. We investigate a sample in the inverted regime where electrons and holes coexist, and compare it with another sample in the non-inverted semiconducting regime. Activated behavior in conjunction with a strong suppression of the resistance peak at the charge neutrality point in a parallel magnetic field attest to the topological hybridization gap between electron and hole bands in the inverted sample. We observe an unconventional Landau level spectrum with energy gaps modulated by the magnetic field applied perpendicular to the quantum wells. This is caused by strong spin-orbit interaction provided jointly by the InAs and the GaSb quantum wells.