Magnetic properties of granular Co-polymer thin films

Composite cobalt-polymer thin films are created by simultaneous metal sputtering and plasma polymerization of propane. The magnetic properties are investigated as a function of Co volume fraction. At low concentration, Co forms very small isolated clusters (∼10 Å) which behave superparamagnetically down to <6 K. At 0.22 ±0.05 Co volume fraction an electrical percolation threshold and a transition to ferromagnetic behavior is observed.