Ferromagnetic enhancement and magnetic anisotropy in nonpolar-oriented (Mn, Na)-codoped ZnO thin films.

High-resistive Zn0.95Mn0.05O and weak p-type nonpolar-oriented Zn0.94Mn0.05Na0.01O thins films were grown on quartz by pulsed laser deposition. Both samples exhibit room temperature ferromagnetism while with Mn-Na codoping, the saturation magnetic moment is greatly enhanced. It is revealed that the doped Mn impurities are substitutionally incorporated into the ZnO host. Magnetic anisotropy was also observed in the Zn0.94Mn0.05Na0.01O film, which is the indication for intrinsic ferromagnetism. The first-principles calculations reveal that codoping of Na in Zn0.94Mn0.05Na0.01O changes the antiferromagnetic interaction to ferromagnetic due to the hybridization between spin-split delocalized Mn 3d and shallow acceptor states of Na 2p, thereby enhancing the ferromagnetism. [ABSTRACT FROM AUTHOR]