Anomalous Conductance Oscillations in the Hybridization Gap of InAs/GaSb Quantum Wells

TL;DR

This paper reports on magnetic conductance oscillations in InAs/GaSb quantum wells, revealing unique in-gap oscillation behavior linked to the insulating bulk, challenging existing theories and proposing a new two-band model.

Contribution

It introduces a novel observation of in-gap conductance oscillations in InAs/GaSb quantum wells and proposes a two-band model to explain their unique properties.

Findings

In-gap oscillation frequency exceeds that near the conduction band edge.

Oscillations are linked to the insulating bulk, confirmed by antiphase behavior.

Temperature effects include thermal activation and smearing, not explained by Lifshitz-Kosevich theory.

Abstract

We observe the magnetic oscillation of electric conductance in the two-dimensional InAs/GaSb quantum spin Hall insulator. Its insulating bulk origin is unambiguously demonstrated by the antiphase oscillations of the conductance and the resistance. Characteristically, the in-gap oscillation frequency is higher than the Shubnikov-de Haas oscillation close to the conduction band edge in the metallic regime. The temperature dependence shows both thermal activation and smearing effects, which cannot be described by the Lifshitz-Kosevich theory. A two-band Bernevig-Hughes-Zhang model with a large quasiparticle self-energy in the insulating regime is proposed to capture the main properties of the in-gap oscillations.