Ferromagnetism in a transition metal atom doped ZnO

Ferromagnetism in a 3d transition metal atom doped ZnO was investigated by ab initio electronic structure calculations based on the local density approximation. It was shown that the anti-ferromagnetic state was stable in Mn atom doped ZnO and the ferromagnetic state was stable in the other transition metal, i.e., V, Cr, Fe, Co or Ni, doped ZnO, if no additional carrier dopant was introduced. Carrier induced ferromagnetism in the Mn atom doped ZnO was also investigated. The results showed that the ferromagnetism was induced by hole doping in the Mn atom doped ZnO. The present calculations will provide us with guidelines to produce ferromagnetic magnetic semiconductors and to control their magnetic state.