Low-field magnetoimpedance of amorphous CoFeSiB alloy wire

Low-field magneto impedance measurements have been performed on (Co0.94Fe0.06)72.5Si12.5B15 amorphous alloy wires at various frequencies. Different magnetization processes are evident at low frequency (5 kHz), where domain wall movements take place, from the processes occurring at higher frequency (100 kHz), where magnetization rotation takes place. Maxima in the DC field dependence of the complex impedance are observed at low as well as at high frequencies in both the real and imaginary parts. The maxima at low fields, with strong hysteresis, are connected to the wall movements within the inner domain structure of the amorphous wire. Another maximum in the DC field dependence of the complex impedance is observed for higher frequency, which does not show hysteresis. Moreover, this second maximum is observed only in the dependence of reactance on the DC magnetic field. This can be ascribed to the magnetization rotation process near the anisotropy field of the outer shell. The effects of the magnitude of the AC current were also studied