Quantum Anomalous Layer Hall Effect in Realistic van der Waals Heterobilayers

The quantum anomalous layer Hall effect (QALHE), characterized by the precise control of the quantum anomalous Hall effect on different layers due to spin-layer-chirality coupling in van der Waals (vdW) layered materials, is of great importance in both fundamental physics and nanodevices. In this work, through the analysis of a low-energy effective model for vdW heterobilayers under biaxial strain, we propose the QALHE in valleytronic materials for the first time. The spin-layer-locked edge states and Chern numbers in heterobilayers give rise to dissipationless currents localized in specific layers, realizing the long-sought QALHE in heterobilayers. The switch of the chirality of edge states and Chern numbers in heterobilayer systems can be achieved by applying a biaxial strain. We have validated this mechanism in a series of realistic valleytronic materials, including VSi₂N₄/VSiCN₄ and RuCl₂/FeCl₂ heterobilayers. Our work reveals a new mechanism for achieving the QALHE with promising applications in spintronics and quantum layertronics.