Magnetism arising from Mexican-hat-like band dispersion in the WSe2/SnS2 heterostructure via interlayer strain

Abstract

Mexican-hat-like band dispersion is extremely critical to the realization of hole-doping-induced magnetism in monolayer metal monochalcogenides. However, it is absent from transition-metal dichalcogenides (TMDCs), i.e., WSe₂. Herein, using first-principles calculations, we show that Mexican-hat-like band dispersion can be achieved by applying interlayer strain (ε) in the WSe₂/SnS₂ van der Waals (vdW) heterostructure when ε exceeds 15%. This is because in the strain-induced distorted trigonal prismatic crystal field, at the valence band edge, the W_d_z² orbitals shift upward around the Γ point, while the double-degenerate W_d_xy/d_x²−y² orbitals shift downward at the K point, resulting in Mexican-hat-like band dispersion near the Γ point when the energy level of the Γ point surpasses that of the K point. On account of the appearance of the Mexican-hat-like band edge (MHBE), hole-doping in the strained WSe₂/SnS₂ heterostructure induces magnetization readily from the nonmagnetized phase. Our findings may provide a new strategy for the realization of magnetized TMDC-based vdW heterostructures.