First-Principles Investigation of a High-Chern-Number Quantum Anomalous Hall Insulator Mn2Bi2O6 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, we report the discovery of a new high-Chern-number quantum anomalous Hall insulator, Mn2Bi2O6. Utilizing first-principles calculations, we systematically investigate its electronic and topological properties. The results reveal that monolayer Mn2Bi2O6 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 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 with 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.