Annealing temperature dependence of transverse permeability spectrum in Co-based amorphous ribbon

The Co-rich amorphous ribbon, Co₆₆Fe₄Si ₁₅B₁₅, was annealed in vacuum under the magnetic field of 3 Oe for 8 h at various temperatures, T_a, between 473 K and 773 K. The MI spectra were measured in the frequency range between 10 kHz to 10 MHz as a function of T_a and the complex transverse permeability spectra were extracted from the MI spectra. The effects of annealing temperature on the magnetization processes are analyzed with static permeabilities and relaxation frequencies of domain-wall motion and magnetization rotation. The static permeabilities show maximum values for the sample annealed around T_a = 623 K, where GMI at various frequencies show maximum ratio.