Ferromagnetic half-metal with high Curie temperature: Janus Mn₂PAs monolayer

Two-dimensional (2D) Janus materials with mirror asymmetry exhibit fascinating physical properties, implying wide applications in nanoscale optoelectronic and piezoelectric devices. However, intrinsic ferromagnetic (FM) Janus monolayers with high Curie temperature (T_c) and large magnetic anisotropic energy (MAE) are rarely reported. By performing the first-principles calculations, the electronic structure and magnetic properties of stable Janus Mn₂PAs monolayer were investigated. We found that Mn₂PAs monolayer is FM half-metal with high T_c of 557 K and easy out-of-plane magnetization axis, as well as a small intrinsic electric polarization. Additionally, Mn₂PAs monolayer under biaxial strain from -10% to 10% remains to be FM half-metallic. More importantly, the MAE reaches a maximum value of ~ 578 μeV per Mn atom under 8% tensile strain and changes direction under compressive strain larger than 2%, which mainly attributes to the variation of (p_y, p_z)/(p_y, p_x) orbital matrix elements of As/P atom. The desired and robust ferromagnetism and half-metallicity with 100% spin-polarization of Janus Mn₂PAs monolayer enrich the application of 2D Janus materials in nanoscale spintronic devices.