Correlation between magnetization processes and giant magnetoimpedance response in CoFeBSi amorphous CoFeBSi wires

Giant magnetoimpedance (GMI) in amorphous (Fe0.06Co0.94)(72.5) B15Si12.5 wi res (submitted to an alternative current, i(ac)) has a dependence of the im pedance response, Z, on direct current magnetic field, H-dc. In as-cast wir es, the ac current frequency changes the GMI: for frequencies of a few kHz, the impedance response is a function of H-dc, having a single maximum at H -dc = 0; for frequencies >1 MHz, however, two maxima (with a minimum at H-d c = 0) are observed. By analyzing the frequency dependence of real, L-r, an d imaginary inductance, L-i (proportional to real and imaginary permeabilit y, respectively), we show that these results can be explained in terms of t he dominant magnetization process: domain wall bulging for low frequencies, and magnetization rotation for high frequencies. Plots of both L-r and L-i as a function of frequency indicate relaxation processes at about 45 kHz, due to a change from domain wall to spin rotation as the dominant magnetiza tion process. (C) 2001 Elsevier Science B.V. All rights reserved.