An ab initio study on the electronic and magnetic properties of MgO with intrinsic defects

Abstract

Using ab initio calculations based on density functional theory with PBEsol/PBEsol + U method, the electronic and magnetic properties of undoped MgO are investigated. Calculated results demonstrate that both neutral and singly charged Mg vacancy can introduce magnetic moment to MgO, and the magnetic moment mainly arises from the spin polarization of the partially occupied 2p orbitals of the nearest O atoms. In combination of group theory and molecular orbital theory, it is found that the magnetic moment is originating from the partially occupied e_g⁻ orbital. Results also demonstrate that closed shell Mg vacancy and all of , and cannot lead to magnetic moment in MgO, but and will change the insulating behavior into n-type conductivity. In MgO with double Mg vacancies, the defects formation energies suggest that two Mg vacancies prefer the next nearest sites to other configurations. In addition, the magnetic coupling induced by two Mg vacancies is mainly due to the p–p hybridization interaction of O atoms. However, the magnetic moment will be drastically reduced or even completely suppressed within PBEsol + U method, and the total density of states reveal that the system with Mg vacancy displays a p-type conductivity character.