Inducing ferromagnetism in ZnO through doping of nonmagnetic elements

In this work, Zn, Al, Pt, Ag, and Au nonmagnetic metallic films were deposited on the surface of ZnO film, followed by high vacuum annealing at different temperatures. Results showed that (Zn, Al, Pt)/ZnO films possessed room temperature ferromagnetism (RTF) after the vacuum annealing, while (Ag, Au)/ZnO films did not. Our detailed structural investigations (transmission electron microscopy and x-ray photoelectron spectroscopy) revealed that this RTF was associated with the presence of metal clusters. The RTF disappeared in Al/ZnO after a subsequent annealing in air, as metal clusters were oxidized. Pt/ZnO remained ferromagnetic, as the metal cluster structure was stable subjected to the air annealing. (C) 2008 American Institute of Physics.