Interlayer Sliding for Magnetic and Topological Phase Control in Pt₂HgSe₃/Nb₃I₈ van der Waals Heterostructure

Abstract

The integration of two-dimensional van der Waals materials provides a powerful platform for engineering quantum states with tailored properties. In this work, we systematically investigate the Pt₂HgSe₃/Nb₃I₈ magnetic heterostructure using first-principles calculations. Upon heterostructure formation, the magnetic proximity effect successfully induces magnetism in the non-magnetic Pt₂HgSe₃ layer, accompanied by a remarkable switching of the easy magnetization axis from in-plane to out-of-plane, which breaks time-reversal symmetry and gives rise to valley polarization. Intriguingly, we reveal that interlayer sliding precisely controls the distribution of induced magnetic moments across different atomic layers. Furthermore, We map the evolution of bandgap, magnetic anisotropy energy, and Chern number as functions of interlayer displacement, revealing a rich phase diagram. The heterostructure can be classified into four distinct categories. A key finding is the switching of MAE sign along a high-symmetry sliding path. We provide a quantitative, spin-resolved analysis to explain this switching mechanism based on second-order perturbation theory, linking it to spin-conserving and spin-flipping transitions between specific Nb d-orbital states. Furthermore, we show that the Chern number can be efficiently modulated between -1, 0, and +1 via layer sliding, enabling access to quantum anomalous Hall phases without external fields. Our results establish interlayer sliding as a robust and feasible method for multidimensional control in van der Waals heterostructures, offering design principles for developing topological spintronics and valleytronics applications.