Tuning the magnetic anisotropy of ferromagnetic MnS2 monolayers via electron occupation of Mn d orbitals

Tuning magnetic anisotropy can facilitate the practical application of two-dimensional ferromagnets. Thus, understanding the relationship between magnetic anisotropy and electronic structures is desirable. Here, using the first-principles calculations and the second-order perturbation analyses, we investigate the microscopic mechanism (or electronic origin) underlying the change of the magnetic anisotropic energy (MAE) of the ${\mathrm{MnS}}_{2}$ monolayer. The calculated results show that strain enables the MAE to transform between an in-plane and off-plane orientation, and interlayer coupling (IC) from heterostuctures induces it to change positively. Furthermore, the strain-induced change in the MAE is greater than its IC-induced change. The further analyses indicate that although the microscopic mechanism underlying the strain- and IC-induced changes of the MAE is distinct, the change in electron occupation of $\mathrm{Mn}\text{\ensuremath{-}}d$ orbitals dominates the two changes. This work confirms the dominance of electron occupation on the MAE change and thus enriches the microscopic understanding about a MAE change, providing a theoretical reference to tuning the MAE of 2D ferromagnetic semiconductors in the future.