O-vacancy-mediated spin-spin interaction in Co-doped ZnO: First-principles total-energy calculations

摘要

The effects of O vacancy (V_O) on the electronic and magnetic properties of Co-doped ZnO are examined through first-principles total-energy calculations. Our results suggest that due to the presence of V_O, O 2p states are coupled with the Co 3d states. Co 3d empty minority states are broadened and move up towards the Fermi level. V_O at metastable sites can induce the ferromagnetic (FM) coupling between nearest-neighbor (NN) Co ions, and the atoms around the FM-coupled NN Co ions are spin-polarized which leads to the long-ranged FM coupling between Co ions. Our results based on first-principles total-energy calculations give a possible explanation for the controversial magnetic properties of Co-doped ZnO reported in the literature.