Influence of thickness and roughness on the anisotropy of asquenched Co-based amorphous magnetic ribbons

Abstract

The magnetic anisotropy of two near-zero-magnetostriction Co-based amorphous ribbons with high and low Curie temperatures was measured by torque magnetometry in samples with different thicknesses. It was found that the thicker ribbons have a lower anisotropy in samples with low T c, whilst in those with high T c the result is inverted, the thicker ones having a larger anisotropy, always along the ribbon axis. This behavior can be interpreted in samples with high T c as being due to an induced anisotropy produced by the alignment of the magnetization along the ribbon axis by the shape effect during the quench. This interpretation would also account for the increase of anisotropy with annealing in these kinds of samples. For lower T c, the induced anisotropy diminishes and the surface roughness anisotropy plays a more important role. Mechanical polishing confirms this assumption.