The interatomic exchange interactions and the electronic structure of Co-doped ZnO with and without oxygen vacancy were investigated by the first-principles calculations based on density functional theory. It was found that the oxygen vacancy could strengthen the ferromagnetic exchange interaction between Co atoms and might be available for carrier mediation. The oxygen vacancy near to the Co atoms was more favorable for the ferromagnetic ground state.

First-Principles Study on Co-Doped ZnO with Oxygen Vacancy. Weng, Z., Huang, Z., Lin, W.: Advanced Materials Research, 2011, 154-155, 124-9