Effects of rapid thermal annealing on the ferromagnetic properties of sputtered Zn1−x(Co0.5Fe0.5)xO thin films

We have investigated the effects of rapid thermal annealing under vacuum on the CoFe-doped ZnO [Zn1−x(Co0.5Fe0.5)xO] films grown by reactive magnetron co-sputtering. At least up to x=0.15, the films have the single phase of the same wurtzite structure as pure ZnO. Ferromagnetism was observed for the CoFe-doped ZnO films. We found that rapid thermal annealing leads to a remarkable increase in the spontaneous magnetization of the CoFe-doped ZnO as well as the electron concentration. The annealing also leads to a significant increase in the Curie temperature (TC), resulting in room temperature ferromagnetism with TC>300 K for the CoFe-doped ZnO films.