Interstitial H+-Mediated Ferromagnetism in Co-Doped ZnS

The ferromagnetic mediation centers of enough high concentration are the prerequisites for the realization of ferromagnetic diluted magnetic semiconductors. Zn0.97Co0.03S ultrafine nanoparticles of diameter Ee4 nm with zinc blende structure were synthesized by the chemical coprecipitation method. After annealing in H-2 atmosphere at 500 A degrees C for 2 h, Zn0.97Co0.03S transformed to wurtzite structure of increased particle size and strongly enhanced room temperature ferromagnetism has been observed. The possible ferromagnetic contribution from metallic Co due to reduction by H-2 has been excluded. Combining the structural characterizations and density functional theory calculations, we conclude that the interstitial H+ ions in wurtzite ZnS may provide efficient ferromagnetic mediation between the neighboring Co2+ ions.