Possible origin of ferromagnetism in pristine magnesium oxide film

Abstract The electronic structure and magnetism of pristine magnesium oxide (MgO) (001) surface have been studied using first principle calculations based on density functional theory (DFT). Our results reveal that isolated magnesium (Mg) vacancy (VMg) can produce a magnetic moment of about 1.99 μB. The magnetic moment mainly comes from p-orbitals of oxygen atoms adjacent to VMg. The surface with one VMg will show half-metallic properties. Studies of magnetic coupling show that the surface with two VMg's will be in a spin singlet state (S = 0) at the distance of 2.98 or 8.42 A between two VMg's, while the two VMg's are coupled ferromagnetically at the distance of 4.21, 5.96, or 6.66 A. As the distance between two VMg's increases, the system will change from semiconductor state to half-metallic state, and finally to metal state. These findings are significant for d0 ferromagnetism in MgO film and useful for spintronic application.