Magnetic Thin Films of Cobalt Nanocrystals Encapsulated in Graphite-Like Carbon

Abstract

ABSTRACTGranular thin films consisting of cobalt nanocrystals encapsulated in graphite-like carbon were fabricated by co-deposition of cobalt and carbon with subsequent annealing. The gram size and the crystal structure of the Co-C films depended on the substrate temperature, the carbon concentration, and the annealing temperature. The film deposited with 36 at.% carbon at 200°C consisted of crystalline carbide and hep cobalt, which transformed into hep cobalt and graphite-like carbon by annealing at ≥300 °C. The as-deposited film with a carbon of 46 at.% had an amorphous-like phase and grain sizes of ≤10 nm. By annealing at ≥300°, the amorphous-like phase transformed into cobalt grains with a random stacking structure encapsulated in graphite-like carbon, and the initial size of the grains was unchanged. The saturation magnetization and the in-plane coercivity of these films were also reported.