First-principles study for ferromagnetism of Cu-doped ZnO with carrier doping

We studied the effects on the ferromagnetism of carrier doping in Zn1−xCuxO with x=0.0277–0.0833 by using the first-principles calculations. The total magnetic moment of Cu is about 1, 2, and 3 μB/cell at the concentration of 2.77%, 5.55%, and 8.33%, respectively. For Zn1−xCuxO1−yNy, we obtained the ferromagnetic and half-metallic ground state. The Cu magnetic moment in low Cu concentration is increased by the N-doping. However, for the F-doping it decreases. The ferromagnetism in Cu-doped ZnO is controllable by changing the carrier density. The N 2p states hybridize well with Cu 3d states instead of the O 2p states. Due to the hybridization between N 2p and Cu 3d states, the holes are itinerant with keeping its 3d states. For (Cu,N)-codoped ZnO, it is recognized that the width of 3d states is larger than that of (Cu,F)-codoped ZnO.