Valence State-Dependent Ferromagnetism in Mn-Doped NiO Thin Films



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Manipulating the ferromagnetism of diluted magnetic semiconductors by tuning the valence state of doped ions is found to be achievable in Mn-doped NiO. First-principles calculations predict that the interactions between substitutional Mn3+ ions in NiO are ferromagnetic, while the Mn2+–Mn2+ interactions are antiferromagnetic. This scenario is experimentally supported by a great enhancement of saturation magnetization with increased Mn3+/Mn2+ ratio in Mn-doped and (Mn, Li)-codoped NiO.