Ferromagnetism in nanocrystalline nickel incorporated diamond-like carbon thin films

Nanocrystalline nickel (Ni) impregnated diamond-like carbon (NiDLC) films were deposited on glass substrates by using capacitatively coupled plasma chemical vapour deposition. Ni nanocrystallite content was modulated by varying the relative amount of argon in the methane and argon plasma. The chemical composition, structural, microstructural and magnetic studies in these NiDLC films were carried out. Presence of Nisingle bondC bonding states could not be supported as no peak related to the characteristic Ni3C phase was present even in the samples with highest Ni content. DLC matrix became more graphitic in nature with increasing Ni content. This observation was in conformity with the findings from the XPS and FTIR studies as well. Magnetization in the films decreased with increase in temperature. Values of the coercive fields were measured under both increasing and decreasing applied magnetic fields. The difference in the coercive fields increased slowly for films containing increased amount of nickel particles in the DLC matrix and then increased significantly for films containing 0.69 At% of nickel.