Room temperature ferromagnetism in ZnO:Cu and ZnO:Ag co-doped with Al

Abstract

Abstract The room temperature ferromagnetism in doped and co-doped ZnO is reported here. X-ray photoelectron spectroscopy revealed the mixed oxidation states of Cu and Ag in ZnO:Cu and ZnO:Ag films, respectively. However, co-doping of Cu and Ag with Al does not alter their bonding characteristics in ZnO. Al in +3 oxidation state indicates that substitution of Al to Zn site gives an extra electron which increases the conductivity of ZnO:Ag and ZnO:Cu films. Mott variable range hopping dominates the conduction in ZnO:Cu and ZnO:Ag films whereas thermally activated conduction dominates in Al co-doped ZnO:Ag and ZnO:Cu films. We show that Ruderman–Kittel–Kasuya–Yosida mechanism is not responsible for ferromagnetism in Cu and Ag doped ZnO as the increase in carrier concentration due to Al co-doping does not enhance the ferromagnetism. Finally, possible mechanism behind the ferromagnetism is discussed.