Tunable quantum anomalous Hall effects in ferromagnetic van der Waals heterostructures.

The quantum anomalous Hall effect (QAHE) has unique advantages in topotronic applications, but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAHE with Chern numbers C  = ±1 and the out-of-plane magnetization induced QAHE with high Chern numbers C  = ±3 can be realized in a single material candidate, which is composed of van der Waals (vdW) coupled Bi and MnBi 2 Te 4 monolayers. The switching between different phases of QAHE can be controlled in multiple ways, such as applying strain or (weak) magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAHE will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.