Quantum anomalous Hall insulator state in ferromagnetically ordered Mn Bi2Te4/V Bi2Te4 heterostructures

The quantum anomalous Hall effect (QAHE) has been experimentally realized in the van der Waals layered topological insulator Mn Bi₂Te₄ . However, the antiferromagnetic order of Mn Bi₂Te₄ restricts the experimental observation of the QAHE at zero magnetic field. Based on first-principle calculations, we find that stacking Mn Bi₂Te₄ with V Bi₂Te₄ , another material from the M Bi₂Te₄ family, can realize a ferromagnetic coupling between layers with an out-of-plane easy axis. The nontrivial topological phase exists in Mn Bi₂Te₄/V Bi₂Te₄ bilayers and multilayers. Mn Bi₂Te₄ is the main source of QAHE, while V Bi₂Te₄ boosts ferromagnetic coupling between the layers. Thus QAHE can be achieved at zero magnetic field in Mn Bi₂Te₄/V Bi₂Te₄ heterostructures, irrespective of odd and even layers. Our finding sheds light on strongly pursuing robust QAHE in van der Waals magnetic topological insulators.