Conversation from anti-ferromagnetic Mn­Br2 to ferromagnetic Mn­3Br8 monolayer with large MAE

Abstract A pressing need in low energy spintronics is two-dimensional (2D) ferromagnets with Curie temperature above the liquid-Nitrogen temperature (77K), sizeable magnetic anisotropy. We studied Mn3Br8 monolayer which is obtained via inducing Mn vacancy at 1/4 population in MnBr2 monolayer. Such defective configuration is designed to change the coordination structure of the Mn-d5, to achieve ferromagnetism with sizeable magnetic anisotropy energy (MAE). Our calculations show that Mn3Br8 monolayer is a ferromagnetic (FM) half-metal and has Curie temperature of 130K, large MAE of -2.33 meV per formula unit, atomic magnetic moment of 13/3µB. Additionally, Mn3Br8 monolayer maintains to be FM under small biaxial strain, whose Curie temperature under 5% compressive strain is 160K. Additionally, both biaxial strain and carrier doping make the MAE increase, which mainly contributed by the magneto-crystalline anisotropy energy (MCE). Our designed defective structure of MnBr2 monolayer provides a simple but effective way to achieve ferromagnetism with large MAE in 2D materials.