Granular magnetic cobalt metal/polymer thin film system

Thin films consisting of granular dispersions of cobalt nano-particles in a hydrocarbon matrix are fabricated by simultaneous sputtering of cobalt and plasma induced polymerization of hydrocarbon monomers. It is confirmed that cobalt nano-particles with a hexagonal close-packed (hcp) structure are uniformly distributed throughout the amorphous hydrocarbon matrix. In-plane magnetic hysteresis loops obtained by MOKE (Magneto-Optic Kerr Effect) magnetometry measurements show significant differences between granular cobalt crystallites dispersed throughout the polymeric film matrix and cobalt crystallites in a continuous polycrystalline pure cobalt film due to the mechanism of domain boundary pinning. For the first time, the domain structures and wall motion in a cobalt/polymer system are captured in real time by Lorentz microscopy.