Long-ranged and high temperature ferromagnetism in (Mn,C)-codoped ZnO studied by first-principles calculations.

We theoretically investigated the electronic structures and magnetic properties of (Mn,C)-codoped ZnO system based on the first-principles calculations within a GGA+U_p,d approach. We found that codoping C is a promising approach to enhance the ferromagnetic coupling between the nearest-neighboring Mn ions due to the strong hybridization between the C:2p and the Mn:3d states. Moreover, the spin-polarized states induced by C are so extended that they can mediate long-ranged ferromagnetic exchange interactions beyond the nearest-neighboring case. Therefore, (Mn,C)-codoped ZnO is expected to be a ferromagnetic semiconductor with long-ranged ferromagnetism and high Curie temperature. [ABSTRACT FROM AUTHOR]