STUDY OF FREQUENCY DEPENDENCIES OF THE COMPLEX MAGNETIC AC-PERMEABILITY AFTEREFFECT IN AMORPHOUS FE64CO21B15 AND FE8CO77B15 ALLOYS

The frequency dependencies of the complex magnetic permeability and it s aftereffect phenomenon in as-cast and annealed Fe64Co21B15 and in as -cast Fe8Co77B15 amorphous ribbons were studied. The measurements of t hese properties were carried out at frequencies between 1 and 120 kHz. The behavior of the frequency dependence of real and imaginary parts of the ac permeability and aftereffect were analyzed using the magneti c domain wall motion model. A change of the restoring force coefficien t and the damping parameter with time was considered for the study of frequency dependency of the magnetic relaxation. (C) 1998 American Ins titute of Physics. [S0021-8979(98)06303-8].