Pressure-induced switching between topological phases in magnetic van der Waals heterostructures

Despite the significant developments in quantum anomalous Hall (QAH) insulators study in recent years, it remains an outstanding challenge to tune between different topological phases in the same material. In this work, an ultrathin van der Waals (vdW) heterostructure based on $\mathrm{Mn}{\mathrm{Bi}}₂{\mathrm{Se}}₄$ and ${\mathrm{Bi}}₂{\mathrm{Se}}₃$ was proposed by using model Hamiltonian and density-functional theory simulations, which was proved to be an excellent tunable QAH platform. Its band gap closes and reopens as hydrostatic pressure increases, with a topological phase transition around the critical pressure of 2.5 GPa. Further analyses reveal the main reason is the enhancement of interlayer interactions and the crystal-field splitting as the interlayer distance decreases. Our work provides clear physical insights and suggests a strategy for experimental realization and control of the QAH effect in real materials.