EFFECTS OF CRYSTALLIZATION ON THE MAGNETIZATION DYNAMICS OF VITROVAC AMORPHOUS RIBBONS

Co-based soft ferromagnetic amorphous ribbons (Vitrovac(R) 6025) were crystallized by annealing at various temperatures (100-250 K below the crystallization temperature, 831 K) for times ranging from 1 to 18 h. The initial permeability was determined from complex permeability plots in the frequency range 5 Hz- 13 MHz. A decrease in initial permeability mu(i) as a function of annealing time was observed for all annealing temperatures. This decrease was sharper at higher temperatures. The domain wall relaxation frequency f0 exhibited inverse behaviour; the product mu(i)f0 was practically constant for all the experiments. It is shown that these results can be interpreted on the basis of a reversible magnetization mechanism of domain wall bowing, and that the decrease in permeability results from increased wall pinning due to crystallization.