Strain-tunable magnetic transition in few-layer 1T-VSe₂

Two-dimensional vanadium diselenide (VSe2) has attracted extensive interest due to its room-temperature ferromagnetism with many potential applications. However, the intrinsic ferromagnetic (FM) ordering is confined to monolayers, which hinders their practical use because of fabrication difficulty. In this work, the effect of strain on magnetic properties of few-layer 1T-VSe2 is studied based on first-principles calculations. Spin-polarized density functional theory calculations indicate that the monolayer is intrinsic FM, while the bilayer, trilayer, and quadlayer 1T-VSe2 are intralayer FM but interlayer anti-ferromagnetic (AFM). The results predict that few-layer 1T-VSe2 can undergo a prominent magnetic transition from AFM to FM and an enhancement of magnetic moment by introducing in-plane tensile strain above 2%. A universal model is proposed to explain the enhanced FM that the structural deformation leads to symmetry breaking of the interlayer orbital hybridization, thus inducing FM of the whole system through an intralayer super-exchange effect. It is further verified on broader materials, including manganese and vanadium chalcogenides. This study provides a feasible route for achieving and modulating FM in two-dimensional materials, which have great significance in practical spintronic devices.