Ferromagnetism and intrinsic half-metallicity of two-dimensional MnN monolayer with square-octagonal structure

The MnN monolayer with square-octagonal structure (so-MnN) is explored using density functional calculations. The results show that theso-MnN monolayer is energetically, dynamically, thermally and mechanically stable, and exhibits the ferromagnetism and intrinsic half-metallicity. The total magnetic moment is 16 μ_Bin unit cell (Mn₄N₄). The energy band of spin-up crosses the Fermi energy level (E_F), while the spin-down channel has semiconductor characteristic with a direct band gap of 3.0 eV at Γ-point. By applying the biaxial strain, the band gap in spin-down channel can be tuned, and theso-MnN monolayer still possesses the characteristic of ferromagnetism and intrinsic half-metallicity. Finally, the Curie temperatureT_Cincreases gradually under biaxial strains from 0 to +3%, while theT_Chas a decreasing trend under the biaxial strains from 0 to -3%.