Two-dimensional intrinsic ferromagnetic half-metals: monolayers Mn3X4 (X = Te, Se, S)

Inspired by the recent progress on the intrinsic two-dimensional (2D) ferromagnetism, we studied three potential 2D magnets (Mn3X4; X = Te, Se, S) by performing the first-principles calculation based on the density functional theory and Monte Carlo simulations. We predicted intrinsic ferromagnetism in monolayers Mn3Te4 and Mn3Se4, which are half-metallic with 100% spin polarization at the Fermi level. The half-metal band gap of monolayers Mn3Te4 and Mn3Se4 is 0.62 and 0.83 eV, respectively. More importantly, the Curie temperatures of Mn3Te4 and Mn3Se4 were estimated to be above the room temperature by performing the Monte Carlo simulations, suggesting ferromagnetic ordering at room temperature. Additionally, we calculated the phonon spectrum, elastic modulus, and performed the ab initio molecular dynamics simulation which proves that monolayers Mn3Te4 and Mn3Se4 are thermally, dynamically and mechanically stable. Plus, mechanical stripping method was proven to be the feasible way to obtain single-layer Mn3X4.