Ab initio study of ferromagnetism in N doped ZnO and its stabilization by Li co-doping

Spin-resolved electronic properties of N doped ZnO is investigated from ab initio calculations based on density functional theory (DFT). It is found that single N atom at O site in ZnO becomes spin polarized with its many neighboring atoms with a total magnetic moment of 1.0 mu_B. Band structure of ZnO doped with 6.25% of N shows a half metallic character with hole states in the minority channel. Though the ferromagnetic coupling is weak in the system, Li co-doping greatly enhance the ferromagnetism. The results of our calculations suggest the possibility of fabricating ZnO based DMS by (N, Li) co-doping.