Room temperature ferromagnetism in Cd-doped ZnO thin films through defect engineering

Room-temperature ferromagnetism is detected in undoped and cadmium-doped ZnO (ZnO:Cd) thin film grown on c-plane sapphire substrate by metal-organic chemical vapor deposition method. To elucidate the origin of ferromagnetism, a theoretical study based on density functional theory is conducted, focusing on the role of the neutral cation vacancy on the appearance of magnetism in Cd-doped ZnO thin film. The calculations revealed that Cd substitution at Zn sites contributes to the long-ranged ferromagnetism in ZnO by lowering the formation energy of Zn vacancies and thereby stabilizing Zn vacancies from which the magnetic moments originate.