MAGNETOIMPEDANCE AFTEREFFECT IN A SOFT-MAGNETIC AMORPHOUS WIRE

A slow relaxation of the high-frequency impedance is observed in a Co6 8.25Fe4.5Si12.25B15 amorphous wire after nucleation of a new domain pa ttern in a previously saturated sample. The observed impedance decay f ollows quasilogarithmic kinetics, and it is probably associated with t he low-field ac magnetic permeability aftereffect of the circular doma in walls. The impedance drop achieves relative amplitudes up to 1%, 16 s after the removal of the saturating external field. The effect is s tudied under typical magnetoimpedance experimental conditions, varying both the ac current amplitude and frequency. Although completely unde sirable for many technical applications, the unique kinetic features o f the impedance aftereffect may be explored to study circular magnetiz ation processes under extreme domain-wall velocities.