Two-dimensional hexagonal manganese carbide monolayer with intrinsic ferromagnetism and half-metallicity

Recent experimentally observed intrinsic ferromagnetism in two-dimensional (2D) van der Waals crystals has ignited substantial interests due to their great potential in spintronic devices. However, their practical applications are hampered by rather low Curie temperature and small magnetic anisotropic energy. Here, we predict from first-principles calculations that the 2D pristine hexagonal manganese carbide (h-MnC) sheet exhibits robust ferromagnetic and half-metallic features with complete spin polarization, sizable magnetic anisotropic energy, and wide half-metallic gap near the Fermi energy level. Moreover, the h-MnC sheet can retain its structure up to the temperature of 1000 K, indicating a highly thermodynamic stability. The Monte Carlo simulations based on the Heisenberg model with single-ion anisotropy predict a Curie temperature of 233 K in 2D h-MnC crystal. We confirm the robustness of the ferromagnetism and half-metallicity against the external strain from −6% to 10%. Also, a feasible experimental fabrication route is proposed to realize the h-MnC monolayer via heterostructure engineering and exfoliation techniques. Overall, the robustness of the half-metallicity in combination with the high-temperature ferromagnetism render the freestanding h-MnC monolayer and even its energetically favorable h-MnC/MoS₂ and h-MnC/MoSe₂ heterostructures quite promising materials for developing practical spintronic nanodevices. (paper)