Experimental realization of an intrinsic magnetic topological insulator

TL;DR

This paper reports the successful experimental creation of high-quality MnBi₂Te₄ thin films, an intrinsic magnetic topological insulator, revealing its magnetic and topological properties and potential for novel quantum phases.

Contribution

First experimental realization of an intrinsic magnetic topological insulator, MnBi₂Te₄, with detailed characterization and demonstration of its magnetic and topological electronic structures.

Findings

MnBi₂Te₄ exhibits Dirac surface states.

The material is an antiferromagnetic topological insulator with ferromagnetic surfaces.

It can host quantum anomalous Hall and axion insulator phases.

Abstract

Intrinsic magnetic topological insulator (TI) is a stoichiometric magnetic compound possessing both inherent magnetic order and topological electronic states. Such a material can provide a shortcut to various novel topological quantum effects but remains elusive experimentally so far. Here, we report the experimental realization of high-quality thin films of an intrinsic magnetic TI---MnBi$_2$Te$_4$---by alternate growth of a Bi$_2$Te$_3$ quintuple-layer and a MnTe bilayer with molecular beam epitaxy. The material shows the archetypical Dirac surface states in angle-resolved photoemission spectroscopy and is demonstrated to be an antiferromagnetic topological insulator with ferromagnetic surfaces by magnetic and transport measurements as well as first-principles calculations. The unique magnetic and topological electronic structures and their interplays enable the material to embody rich quantum phases such as quantum anomalous Hall insulators and axion insulators in a well-controlled way.