Intrinsic magnetic topological insulators in van der Waals layered MnBi$_2$Te$_4$-family materials

TL;DR

This paper predicts that MnBi$_2$Te$_4$-family materials exhibit various topological quantum effects, including axion states, Weyl semimetals, and quantum anomalous Hall effects, making them promising platforms for future topological physics research.

Contribution

It introduces the prediction of rich topological phenomena in MnBi$_2$Te$_4$ materials, including 3D antiferromagnetic topological insulators and magnetic Weyl semimetals, based on their magnetic and electronic properties.

Findings

MnBi$_2$Te$_4$ is a 3D antiferromagnetic topological insulator with axion states.

The material exhibits a type-II magnetic Weyl semimetal phase with one pair of Weyl points.

It shows potential for high-temperature intrinsic quantum anomalous Hall effect.

Abstract

The interplay of magnetism and topology is a key research subject in condensed matter physics and material science, which offers great opportunities to explore emerging new physics, like the quantum anomalous Hall (QAH) effect, axion electrodynamics and Majorana fermions. However, these exotic physical effects have rarely been realized in experiment, due to the lacking of suitable working materials. Here we predict that van der Waals layered MnBi$_2$Te$_4$-family materials show two-dimensional (2D) ferromagnetism in the single layer and three-dimensional (3D) $A$-type antiferromagnetism in the bulk, which could serve as a next-generation material platform for the state-of-art research. Remarkably, we predict extremely rich topological quantum effects with outstanding features in an experimentally available material MnBi$_2$Te$_4$, including a 3D antiferromagnetic topological insulator with the long-sought topological axion states, the type-II magnetic Weyl semimetal (WSM) with simply one pair of Weyl points, and the high-temperature intrinsic QAH effect. These striking predictions, if proved experimentally, could profoundly transform future research and technology of topological quantum physics.