Edge states and integer quantum Hall effect in topological insulator thin films

TL;DR

This paper investigates the edge states and Landau levels of surface Dirac fermions in topological insulator thin films under strong magnetic fields, revealing patterns of quantum Hall conductance and the breakdown of quantum spin Hall effect.

Contribution

It provides a detailed analysis of quantum Hall states, phase diagrams, and the impact of structure inversion asymmetry on topological insulator thin films.

Findings

Two patterns of quantum Hall conductance plateaux identified

Breakdown of quantum spin Hall effect due to inversion asymmetry

Phase diagrams as functions of magnetic field, gate voltage, and chemical potential

Abstract

The integer quantum Hall effect is a topological state of quantum matter in two dimensions, and has recently been observed in three-dimensional topological insulator thin films. Here we study the Landau levels and edge states of surface Dirac fermions in topological insulators under strong magnetic field. We examine the formation of the quantum plateaux of the Hall conductance and find two different patterns, in one pattern the filling number covers all integers while only odd integers in the other. We focus on the quantum plateau closest to zero energy and demonstrate the breakdown of the quantum spin Hall effect resulting from structure inversion asymmetry. The phase diagrams of the quantum Hall states are presented as functions of magnetic field, gate voltage and chemical potential. This work establishes an intuitive picture of the edge states to understand the integer quantum Hall effect for Dirac electrons in topological insulator thin films.