Room-temperature ferromagnetism in co-sputtered Zn1–xCrxO films with low Cr content

Zn1–xCrxO films with low Cr content were prepared using the co-sputtering method. With increasing x, an increase in the amount of the Cr2O3 phase was found, which was accompanied by a decrease in the saturated magnetization in Zn1–xCrxO films. The normalized photoluminescence spectra clearly demonstrated that the emission due to VZn decreases monotonically in intensity with increasing x. We suggest that the Cr ion substitution is necessary for establishing ferromagnetism in ZnO films containing VZn.