Biaxial strain tuned magnetic anisotropy of ferromagnetic penta-MnN2 monolayer

Abstract

Abstract Ferromagnetic (FM) materials with high Curie temperature, large spin polarization ratio and large perpendicular magnetic anisotropic (PMA) are the basis of constructing practical spintronic devices. Using first-principles calculations, electronic property, magnetism and magnetic anisotropic energy (MAE) of penta-MnN2 monolayer are investigated. The calculated results indicate that penta-MnN2 monolayer is FM half-metal and exhibits PMA. The PMA is induced by Mn atom of 0.207 meV/Mn, which is one or two orders of magnitude larger than those of bulk Co (−65 μeV/atom), Fe (−1.4 μeV/atom) and Ni (2.7 μeV/atom). It is worth noting that the structure, magnetism and MAE of penta-MnN2 monolayer can be manipulated by applying biaxial strain. By applying tensile strain of 3%, penta-MnN2 monolayer has a second energy minimum and remains the original crystalline symmetry, but the N–N bond length has a sudden change. The MAE of Mn atom in penta-MnN2 monolayer can be enhanced by 21% with compressive strain compared to the unstrained systems. Meanwhile, the MAE decreases with the increase of tensile strain, and it exhibits a more significant decrease due to the sudden drop of N–N bond with tensile strain. These results may broaden the development of two-dimensional (2D) FM materials, which have potential applications in 2D spintronic nanodevices.