Abstract
Detailed guidelines for controlling magnetic states in ZnO-based diluted magnetic semiconductors are given based on ab initio electronic structure calculations within the local spin density approximation using the Korringa-Kohn-Rostoker method. Effects of disorder were taken into account by the coherent potential approximation. It was found that the ferromagnetic state was stabilized by electron doping in the case of Fe-, Co- or Ni-doped ZnO. From the view point of practical applications, it is possible to realize a high-Curie-temperature ferromagnet, because n-type ZnO is easily available.