Magnetic properties of soft ferrites and amorphous ribbons up to radiofrequencies

Abstract

Significant results are reported concerning the magnetic behavior of sintered soft ferrites and very thin Co-based amorphous ribbons up to 1 GHz. Conveniently field-annealed amorphous tapes can exhibit, in spite of their metallic character, superior combination of magnetic loss and permeability properties at all frequencies. Such properties are phenomenologically assessed through a physical approach based on the statistical theory of losses and the generalization of the related concept of loss separation, which takes into account different dissipation mechanisms and discriminates between domain wall and rotational processes. The latter, in particular, are described in ferrites in association with spin precession and damping and are given a formulation based on the Landau–Lifshitz–Gilbert equation and the assumption of distributed effective anisotropy fields.