Cr3X2Y2 (X, Y = S, Se, Te) Monolayers: Valley-Polarized Quantum Anomalous Hall Insulator Driven by Electric Field

Abstract

The valley-polarized quantum anomalous Hall (VP-QAH) insulators, combining valleytronics and topology in materials, have promising applications in low-power-consumption spintronic devices. Based on tight-binding (TB) model and first principles calculations, we predict that Cr3X2Y2 (X, Y = S, Se, Te) monolayer is ferromagnetic (FM) Weyl semimetal with out-of-plane magnetization easy axis. When the spin-orbit-coupling (SOC) effect is considered, the Weyl point is opened, giving rise to QAH effect with Chern number C = 1. Moreover, it is found that the Cr3X2Y2 monolayer exhibit VP-QAH effect when an external electric field is applied due to the breaking of the C2xT symmetry, and the valley polarization value increases with the enhancement of the electric field. Specially, the Curie temperature, electronic structure and topological bandgap of Cr3X2Y2 monolayer can be modulated by biaxial strains. Our results suggest that this Cr3X2Y2 monolayer provides a potential platform for designing spintronic devices.