Effects of codoping on the ferromagnetic enhancement in ZnO

The present work investigates the effect of the anionic codoping on the magnetic properties of the dilute magnetic semiconducting materials doped with transition-metal (TM) ions, namely, that of Zn(Mn, X)O, X = C, N, P, and S. The present findings are in complete analogy with the corresponding results for the cationic codoping of Zn(TM1, TM2)O as studied in our earlier works. For both the cationic and anionic codopings, we find that the magnetic impurities induce magnetic moments on their nearest neighbors, with the largest induced magnetic moment observed on the cation or the anion which mediates two magnetic impurities. The magnetic interaction in the case of the anionic codoping can be seen as a generalized double exchange or a superexchange type of mechanism similar to that found in the cationic codoping in which the magnetic interactions take the form of a double exchange or a superexchange between polarized tetrahedra each centered at one of the codopants.