# Pursuing High-Temperature Quantum Anomalous Hall Effect in MnBi$_2$Te$_4$/Sb$_2$Te$_3$ Heterostructures

## TL;DR

This paper proposes a novel MnBi$_2$Te$_4$/Sb$_2$Te$_3$ heterostructure that intrinsically exhibits high-temperature quantum anomalous Hall effect due to engineered ferromagnetic coupling and topological properties.

## Contribution

It introduces a new heterostructure design that achieves high-temperature QAHE without external magnetic fields, based on theoretical modeling and band structure analysis.

## Key findings

- Interlayer ferromagnetic transition at 42 K.
- Topologically nontrivial band gap of 26 meV.
- Hosts QAHE with Chern number 1.

## Abstract

Quantum anomalous Hall effect (QAHE) has been experimentally realized in magnetically-doped topological insulators or intrinsic magnetic topological insulator MnBi$_2$Te$_4$ by applying an external magnetic field. However, either the low observation temperature or the unexpected external magnetic field (tuning all MnBi$_2$Te$_4$ layers to be ferromagnetic) still hinders further application of QAHE. Here, we theoretically demonstrate that proper stacking of MnBi$_2$Te$_4$ and Sb$_2$Te$_3$ layers is able to produce intrinsically ferromagnetic van der Waals heterostructures to realize the high-temperature QAHE. We find that interlayer ferromagnetic transition can happen at $T_{\rm C}=42~\rm K$ when a five-quintuple-layer Sb$_2$Te$_3$ topological insulator is inserted into two septuple-layer MnBi$_2$Te$_4$ with interlayer antiferromagnetic coupling. Band structure and topological property calculations show that MnBi$_2$Te$_4$/Sb$_2$Te$_3$/MnBi$_2$Te$_4$ heterostructure exhibits a topologically nontrivial band gap around 26 meV, that hosts a QAHE with a Chern number of $\mathcal{C}=1$. In addition, our proposed materials system should be considered as an ideal platform to explore high-temperature QAHE due to the fact of natural charge-compensation, originating from the intrinsic n-type defects in MnBi$_2$Te$_4$ and p-type defects in Sb$_2$Te$_3$.