Quantum Transport in Magnetic Topological Insulator Thin Films

TL;DR

This paper develops a quantum transport theory for magnetic topological insulator thin films, explaining experimental observations of the quantum anomalous Hall effect and related conductance behaviors through a topologically nontrivial conduction band with Berry curvature.

Contribution

It introduces a theoretical model that accurately describes transport phenomena in magnetic topological insulator thin films, highlighting the roles of symmetry breaking and Berry curvature.

Findings

Transport originates from a topologically nontrivial conduction band.

Broken inversion and particle-hole symmetries are crucial.

The model aligns well with experimental data.

Abstract

The experimental observation of the long-sought quantum anomalous Hall effect was recently reported in magnetically doped topological insulator thin films [Chang et al., Science 340, 167 (2013)]. An intriguing observation is a rapid decrease from the quantized plateau in the Hall conductance, accompanied by a peak in the longitudinal conductance as a function of the gate voltage. Here, we present a quantum transport theory with an effective model for magnetic topological insulator thin films. The good agreement between theory and experiment reveals that the measured transport originates from a topologically nontrivial conduction band which, near its band edge, has concentrated Berry curvature and a local maximum in group velocity. The indispensable roles of the broken structure inversion and particle-hole symmetries are also revealed. The results are instructive for future experiments and transport studies based on first-principles calculations.