Effect of heat treatment on transport and magnetic properties of Co-based amorphous alloys

Magnetotransport and magnetic properties of Co66Fe4B15Si15 amorphous ribbons, annealed in vacuum and in open air for various times, are studied. The air-annealed samples exhibit the presence of the near-surface hard magnetic layer. The anomalous Hall effect coefficient and the resistivity change simultaneously under heat treatment with slightly non-linear correlation between them. Positive magnetoresistance in low fields changes to negative magnetoresistance with increase of magnetic field. We explain both positive and negative magnetoresistance in terms of spin-dependent scattering.