Ferromagnetism in Fe‐doped ZnO bulk samples with additional Cu doping

Room-temperature (RT) ferromagnetism (FM) has been observed in Fe-doped ZnO bulk samples fabricated by a coprecipitation method, and the effect of additional Cu doping on magnetic properties of the samples has been investigated. The results of XRD show that all doping samples are single-phase with a wurtzite structure. X-ray photoelectron spectroscopy reveals that Fe is in 3+ state substituting for Zn in the sample without Cu doping, however, Fe shows a mixed oxidation state of 2+ or 3+ in the sample with additional Cu doping, where Cu is 1 + valence. Magnetic measurements indicate that additional Cu doping enhances the FM of the system, and the magnetization increases gradually with the increasing Cu content x up to 1%. The observed RT FM was attributed to the ferromagnetic coupling between Pe 3+ ions mediated by holes.