Gate-Tunable Quantum Anomalous Hall Effects in MnBi$_2$Te$_4$ Thin Films

TL;DR

This paper demonstrates that the quantum anomalous Hall effect in MnBi₂Te₄ thin films can be tuned using electrical gate fields, enabling control over topological phase transitions with potential for electronic applications.

Contribution

It introduces a method to optimize QAH gaps and induce topological phase transitions in MnBi₂Te₄ thin films via electrical gating, combining a coupled-Dirac-cone model with self-consistent calculations.

Findings

QAH gaps can be optimized in MnBi₂Te₄ thin films.

Electrical gate fields can induce topological phase transitions.

Transitions occur at approximately 10 meV/nm scale.

Abstract

The quantum anomalous Hall (QAH) effect has recently been realized in thin films of intrinsic magnetic topological insulators (IMTIs) like MnBi$_2$Te$_4$. Here we point out that that the QAH gaps of these IMTIs can be optimized, and that both axion insulator/semimetal and Chern insulator/semimetal transitions can be driven by electrical gate fields on the $\sim 10$ meV/nm scale. This effect is described by combining a simplified coupled-Dirac-cone model of multilayer thin films with Schr{\"o}dinger-Poisson self-consistent-field equations.