Room-Temperature Ferromagnetism Induced by Zn Vacancy Enhancement Through ZnO Nanostructure Modification

Undoped ZnO nanostructures were deposited on Si (100) substrate using direct-current-unbalanced magnetron sputtering. The nanostructure modification of conelike into rod-shaped nanocolumnars is found after thermal annealing with O2. This modification transforms paramagnetism into room-temperature ferromagnetism, induced by Zn vacancy enhancement at the cost of O vacancies. First principles confirm that the ferromagnetism comes from O 2p holes due to Zn vacancies. Our result shows the crucial role of ZnO nanostructure modification in inducing ferromagnetism for novel functional device applications.