Ferromagnetism in sputtered Co doped CeO2 thin film on Al 2O3 (0001) substrate

Abstract

Diluted Co doped CeO2 films with the stoichiometry of Ce 0.97Co0.03O2-d have been prepared via long range magnetron sputtering under varied O2 flux. Films were thoroughly characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmission spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and magnetic measurements. The results indicate all film are ferromagnetism (FM) at room temperature, of which the saturated magnetization moments (M S) are changed according to the O2 pressure adopted in deposition. This phenomenon is well consistent with the oxygen vacancy (V O, or so called F-center) mediated FM mechanism which was recently proposed to interpret FM found in insulating diluted magnetic oxides (DMOs) system. For further exploration of the oxygen dependent of the MS, oxygen non-stoichiometry was characterized by XPS. It shows that film deposited at lower O2 pressure contains less oxygen weight or more oxygen vacancies, lead to an enhanced MS and vice versa. © 2009 IOP Publishing Ltd.