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

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 $T_{\mathrm{C}}=42\mathrm{K}$ 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${}_3$.