Pursuing High-Temperature Quantum Anomalous Hall Effect in MnBi2Te4/Sb2Te3 Heterostructures
Abstract
Quantum anomalous Hall effect (QAHE) has been experimentally realized in magnetically-doped topological insulators or intrinsic magnetic topological insulator MnBi2Te4 by applying an external magnetic field. However, either the low observation temperature or the unexpected external magnetic field (tuning all MnBi2Te4 layers to be ferromagnetic) still hinders further application of QAHE. Here, we theoretically demonstrate that proper stacking of MnBi2Te4 and Sb2Te3 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 C=42~ K when a five-quintuple-layer Sb2Te3 topological insulator is inserted into two septuple-layer MnBi2Te4 with interlayer antiferromagnetic coupling. Band structure and topological property calculations show that MnBi2Te4/Sb2Te3/MnBi2Te4 heterostructure exhibits a topologically nontrivial band gap around 26 meV, that hosts a QAHE with a Chern number of 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 MnBi2Te4 and p-type defects in Sb2Te3.