Reduction of defect-induced ferromagnetic stability in passivated ZnO nanowires

First-principles calculations are performed to study the electronic structures and magnetic properties of ZnO nanowires (NM). Our results indicate that the single Zn defect can induce large local magnetic moment (～ 2μ_B) in the ZnO NWs, regardless of the surface modification. Interestingly, we find that local magnetic defects have strong spin interaction, and favor room-temperature ferromagnetism in bared ZnO NW. On the other hand, although H passivation does not destroy the local magnetic moment of Zn vacancy, it does greatly reduce the spin interaction between magnetic defects. Therefore, our results indicate that H passivation should be avoided in the process of experiments to maintain the room-temperature ferromagnetism.