Measuring the Chern number with quantum oscillations

TL;DR

This paper proposes a method to measure the Chern number and detect topological phase transitions in topological insulator surface states by analyzing quantum oscillations, leveraging their particle-hole asymmetry.

Contribution

It introduces a novel approach to determine the Chern number through quantum oscillation measurements in topological insulators, considering effects of Zeeman field and surface hybridization.

Findings

Chern number can be measured via quantum oscillations in topological insulators.

Topological phase transition from quantum spin Hall to quantum anomalous Hall is detectable.

Particle-hole asymmetry is essential for this measurement method.

Abstract

A peculiar feature of the majority of three dimensional topological insulator surface states studied experimentally thus far, namely their particle-hole asymmetry, makes quantum oscillations (Shubnikov de Haas and de Haas van Alphen oscillations) in these materials particularly rich. I show that this peculiarity can be exploited to measure the Chern number, and detect topological phase transitions in topological insulator surface states from the quantum spin Hall phase to the quantum anomalous Hall phase. I consider the behaviour of quantum oscillations in topological insulator thin film surface states in the presence of a topological exciton condensate, or hybridisation between the two surfaces. As a function of Zeeman field, the Chern number and phase transition from a quantum spin Hall to a quantum anomalous Hall phase can be measured using standard techniques. This effect relies necessarily on the particle-hole asymmetry which is ubiquitous in currently know materials that exhibit topological insulator surface states.