Roles of oxygen vacancy on ferromagnetism in Ni doped In₂O ₃: A hybrid functional study

The roles of oxygen vacancies on the electronic and magnetic properties of Ni doped In₂O₃ have been studied by first-principles calculations based on hybrid functional theory. Our results predict that the Ni-doped In₂O₃ system displays a ferromagnetic semiconducting character. However, the presence of oxygen vacancies results in antiferromagnetic coupling between the neighboring Ni pair bridged by an oxygen vacancy. The antiferromagnetic coupling is found to arise from the predominant role of superexchange due to the strong Ni 3d-O 2p hybridization. Consequently, the oxygen vacancies play a key role in the lower saturation magnetization of Ni:In₂O₃ polycrystalline sample, as observed in experiments.