The structure and magnetic properties of sputtered, amorphous CoFeSiB thin films

Amorphous wires and ribbons of composition Co_70.5Fe_4.5Si₁₅B₁₀ have a very small magnetostriction and very low coercivities for wall motion. Their high permeabilities are of considerable technological interest. Thin films of these alloys might be useful for applications, but had not been previously studied. This work studied the structural and magnetic properties of amorphous thin films sputtered from an alloy target with the composition Co_70.5Fe_4.5Si₁₅B₁₀ . The results obtained show that the coercivity and in-plane anisotropy of the sputtered films are much larger than those of ribbons and wires. Attempts to reduce these parameters by varying the processing and annealing parameters, substrate material, composition, and film thickness were largely unsuccessful. While these results are not understood, the composite data suggests that the higher values may be due to micro-compositional inhomogeneities resulting from higher effective quench rates of sputtering