Abstract: The microstructural and magnetic properties of Ni1-xMnxO (001≤x≤005) thin films prepared by pulsed laser deposition (PLD) were studied by combining X-ray absorption near edge structure (XANES) spectroscopy, superconducting quantum interference device (SQUID) and first-principles calculations. XANES results at Mn K-edge show that at the low Mn doping level of x≤003, the Mn ions in the mixed oxidation valence state (+2/+3) are incorporated substitutionally into the NiO host, while at higher doping level of x>003 Mn2O3-like impurity phase is formed. Magnetization measurements indicate that the saturation magnetic moment of Ni1-xMnxO film increases from 03 to 045 μB/Mn as the Mn content rises from 001 to 003. It is proposed that interactions between Mn3+ ions mediated by Ni vacancies exhibit ferromagnetic coupling, while interactions between Mn2+ ions exhibit antiferromagnetic coupling through superexchange interaction.

Key words: Mn-doped NiO, XAFS, room temperature ferromagnetism