Structures and magnetic properties of Mn-doped NiO thin films

Ni(1-x)Mnx(O) (0.01 <= x <= 0.03) thin films exhibiting p-type conductivity and room-temperature ferromagnetism (FM) were grown by pulsed laser deposition. The x-ray absorption fine structure spectra results at the Mn K edge indicate that the Mn impurities are incorporated substitutionally into the NiO host, and are in the mixed oxidation state (+2/+3). Magnetization measurements show enhanced saturation magnetic moment of Ni1-xMnxO with increased content of Mn3+ ions, suggesting tight correlation of FM to Mn3+ rather than to Mn2+ ions. The first-principles calculations suggest that the strong hybridization between the Mn3+ 3d states and a Ni-vacancy-induced acceptor state accounts for the room-temperature FM of the Ni1-xMnxO films.