Electronic structure and ferromagnetism of transition-metal-impurity-doped zinc oxide

摘要

The ferromagnetism in ZnO-based diluted magnetic semiconductors (DMSs) is investigated based on the first principles calculations. The electronic structure of a ZnO-based DMS is calculated using the Korringa―Kohn―Rostoker method combined with the coherent potential approximation based on the local density approximation. The stability of the ferromagnetic state compared with that of the spin-glass state is systematically investigated by calculating the total energy difference between them. It is found that the ferromagnetic state is more stable than the spin-glass state in V-, Cr-, Fe-, Co- or Ni-doped ZnO without any additional carrier doping treatments. In the case of the Mn-doped ZnO, the spin-glass state is stable at a carrier concentration of 0%, but the ferromagnetic state is stabilized by the hole doping treatment. Analyzing the calculated density of states, it is proposed that the origin of the stabilization of the ferromagnetism is a double-exchange mechanism.