Interlayer interaction controllable multiple anomalous Hall effect in bilayer Janus structures

Abstract

The valley quantum anomalous Hall effect (VQAHE) is of great importance in condensed matter physics and materials science, yet it rarely occurs in intrinsic materials and typically relies on persistent electric fields. Herein, we propose a mechanism for VQAHE by integrating topological physics with multiferroics via a tight-binding model. The broken time-reversal symmetry, coupled with valley physics, induces a large Berry curvature for Bloch electrons in one valley. Combined with inversion symmetry breaking, this mechanism causes directional electron deflection within a layer, thus generating a layer Hall effect to realize layer-locked VQAHE, which is ferroelectrically controllable. First-principles calculations validate this mechanism in the bilayer multiferroic TiTeCl, which also exhibits nontrivial topological phenomena under strain engineering at the Cl–Te interface. Our findings offer in-depth insights into VQAHE and 2D materials research.