Large perpendicular magnetic anisotropy, high curie temperature, and half-metallicity in monolayer CrSI induced by substitution doping

The experimental discovery of two-dimensional (2D) intrinsic ferromagnets have sparked intense interest due to their potential applications in spintronics. However, the small magnetic anisotropy and low Curie temperature (TC) hinder their applications. Herein, through comprehensive first-principles calculations and Monte Carlo simulations, we investigate how Mn substitution doping affects the structure, electronic structure, magnetic properties, and TC of monolayer CrSI. Our calculations show that in contrast to ferromagnetic semiconductor with a TC of 175 K of monolayer CrSI, Mn doped monolayer CrMnS2I2 is a half-metallic ferromagnet with a TC of 312 K. Different from in-plane magnetic anisotropy of monolayer CrSI, the easy axis of monolayer CrMnS2I2 is out-of-plane, and the magnetic anisotropy of monolayer CrMnS2I2 can reach to 1.434 meV/atom, which is much larger than 0.001 meV/atom of monolayer CrSI. Additionally, the phonon dispersion, ab initio molecular dynamics simulations, formation energy, and elastic constants calculations indicate that monolayer CrMnS2I2 possesses excellent stability. Our findings provide a promising route to realize 2D intrinsic ferromagnetic half-metallic materials with a high TC and a large perpendicular magnetic anisotropy.