Strain-controllable high Curie temperature and magnetic anisotropy in two-dimensional Janus 2H-VXY (X, Y = S, Se and Te, X ≠ Y)

Two-dimensional (2D) ferromagnetic (FM) materials with big magnetic anisotropy energy (MAE) and high Curie temperature (Tc) are highly desirable for magnetic storage devices. VXY (X, Y = S, Se and Te, X ≠ Y) monolayers exhibit exciting FM behavior, owing to the super-exchange interaction. Moreover, we find that the in-plane magnetic anisotropy energy of VSSe, VSTe and VSeTe monolayers respectively can reach up to −0.74 meV, −2.78 meV and −3.01 meV per cell in the absence of strain. Compressive strain can further enhance the in-plane magnetic anisotropy energy of VSSe, VSTe and VSeTe monolayers by 76%, 30.4% and 68.9%, respectively. In addition, the in-plane magnetic anisotropy in VXY monolayers switched to out-of-plane magnetic anisotropy under proper tensile strain, which is more conducive to high-density magnetic storage. Furthermore, the exchange splitting and the ligand-field splitting of dxy/dx2−y2 and px/py orbitals significantly regulate magnetic anisotropy energy under the biaxial strain. We predict that the Curie temperature of VSSe, VSTe and VSeTe monolayers are 300 K, 280 K and 410 K by using Monte Carlo simulations based on the Ising model, which can be further increased by applying a tensile stress. These excellent stress-tunable properties give VXY monolayers a broad application prospect in the field of high-density magnetic storage and room temperature spintronics.