Hydrogen-mediated spin-spin interaction in ZnCoO

The effect of hydrogen impurities on the electronic and magnetic properties of ZnO-based diluted magnetic semiconductors is examined through first-principles pseudopotential calculations. We suggest that interstitial H can mediate a strong short-ranged ferromagnetic spin-spin interaction between neighboring magnetic impurities through the formation of a bridge bond. Results based on first-principles total-energy calculations and Monte Carlo simulations indicate that such H-mediated spin-spin interactions can lead to high temperature ferromagnetism.