Spin-chirality-dependent modulation of topological gap, Chern number, and valley polarization in monolayer kagome lattice Cr3Se4

Abstract

Kagome materials exhibit unique electronic properties, such as the quantum anomalous Hall effect. The control of Chern numbers is critical for quantum device manipulation, but existing research has mainly focused on collinear magnetization while neglecting chiral spin textures. Through first-principles calculations and tight-binding modeling of monolayer Cr3Se4, this study reveals spin-chirality-dependent control of topological gaps, Chern numbers, and valley polarization in kagome materials. The results demonstrate that the azimuthal angle has no observable effect. For collinear magnetization (κ = 0) or spin-chirality κ = −1, the topological bandgap decreases as the spin orientation approaches the in-plane direction. Conversely, increasing the polar angle enhances the bandgap for κ = 1. In the breathing kagome lattice, the degeneracy between K and Kʹ valleys is lifted. As the gap undergoes sequential closure and reopening in the two valleys, the structural asymmetry and spin-chirality allow for controlled tuning of the topological gap, Chern number, and valley polarization. Moreover, the emergence of a topological Hall effect is also demonstrated. These findings provide strategies for controlling topological states and advancing applications in quantum devices and valleytronic systems.