Prediction of high spin polarization and perpendicular magnetic anisotropy in two dimensional ferromagnetic Mn2CXX’ (X, X′=F, Cl, Br, I) Janus monolayers

Abstract

Two dimensional layered transition metal carbides and nitrides, owing to their unique electronic properties, have potential applications in novel low-dimensional spintronic devices. However, only a few materials with half metallic and easy axis in perpendicular direction make possible for practical applications in spintronics. Here, the electronic structure and magnetic anisotropy of Mn2CXX’ (X, X' = F, Cl, Br, I) Janus monolayers are investigated by first-principles calculations. It is found that the Mn2CXX′ Janus monolayers are half metallic, showing a high spin polarization at Fermi level. The magnetic anisotropy of Mn2CXX′ monolayers can be modulated by replacing the adsorbed atoms. Mn2CFCl, Mn2CClI and Mn2CClBr show easy axis in perpendicular direction, while the easy axis of Mn2CFBr is in-plane direction. When biaxial strains are −2%, ±4 % and −6%, the easy axis direction of Mn2CClI changes from out-of-plane to in-plane, where the total magnetic anisotropy of I atom can be regulated. The easy axis in in-plane direction comes from the hybridization between I-pz and I-px orbital. However, the easy axis of Mn2CClI maintains perpendicular direction at biaxial strains of 2 % and 6 %. The Mn2CXX′ monolayers with half metallicity and easy axis in perpendicular direction have the potential applications in spintronic devices.