Influence of Oxygen Vacancies on the Magnetic Properties of Zn1 – xCo x O y Films

Thin films of Zn1 – xCo x O y (х = 0–0.3) with a temperature of the ferromagnetic transition of ТС > 300 K are obtained from ZnO–Co3O4 ceramic targets. The electron concentration in the films is found to decrease exponentially with increasing cobalt content. It is revealed that the magnetization of the films obtained under oxygen deficiency conditions varies in a nonmonotonous way as the cobalt concentration increases. This is caused by the oxidation of metallic nanoclusters of cobalt due to an increase in the oxygen content in the targets. Investigation of the transmission spectra of Zn1 – xCo x O y films revealed extrema in the visible region of the spectrum and near the edge of the fundamental absorption band, associated with electron states introduced by cobalt.