Frequency characteristics of permeability in weak-field annealed Co-based amorphous ribbon

The Co-based amorphous ribbons were annealed under the weak-field of a few hundred A/m at a temperature of 380°C for 8 h in an air atmosphere. The annealing field Ha was applied along the sample axis during the annealing to develop the bias field in crystalline layer on the sample surface. Two relaxation due to wall motion and rotational magnetization are revealed in low and high frequency region, respectively, for as-quenched and annealed samples in vacuum under zero field. For the annealed samples in air, the low frequency relaxation due to domain wall motion drastically decreases, while the high frequency relaxation due to rotational magnetization remains irrespective of Ha These results indicate that the wall of longitudinal domains are strongly coupled with the bias field, while the rotational magnetization is enhanced in the annealed samples under the field.