GMI measurements in ribbons of Co70.4Fe4.6Si15B10 in a wide range of frequencies

Abstract This paper reports room-temperature giant magnetoimpedance (GMI) data, measured in samples made of pieces of ribbons of amorphous Co70.4Fe4.6Si15B10 in the microwave frequency range ( f= 2–12 GHz) , for magnetic fields H up to 0.2 T. The measurements were carried out using the samples as one of the conductors of a microstrip line terminated by a short and connected to a network analyzer. We found that values of H, corresponding to the position of the peaks in the impedance spectrum and the peak widths, increase with f. Both the f- and H-dependence of the GMI are in good agreement with a theoretical model based on the dynamics of the domain walls at low f and on the ferromagnetic resonance at high f.