First-Principles Investigation of a High-Chern-Number Quantum Anomalous Hall Insulator MnBiO and Its BN-Coupled Multilayer Heterostructures.

In modern condensed matter physics, the quantum anomalous Hall effect (QAHE), an important manifestation of topological quantum states, has attracted much attention due to its ability to exhibit the quantum Hall effect without the need for an external magnetic field. In this study, the discovery of a new high-Chern-number quantum anomalous Hall insulator, MnBiO is reported. Utilizing first-principles calculations based on density functional theory (DFT), its electronic and topological properties are systematically investigated. The results reveal that monolayer MnBiO possesses a remarkable energy gap of 110 meV and a Chern number of 3, corresponding to three intrinsic conductive edge channels. The material exhibits both strong robustness and stability upon applied strain. Moreover, by stacking double layers with a boron nitride (BN) insulating layer, a heterostructure system with a larger bandgap (117.4 meV) and an increased Chern number of 6 can be realized. When substituting the upper layer's oxygen atoms with tellurium atoms, it forms a Janus structure, accompanied by a transition of Chern number from 3 to 1. This work not only introduces new candidates for expanding the class of QAHE materials but also establishes a new platform for applications in low-power electronic devices and topological quantum computing.