Giant magneto-impedance and its relaxation in Co–Fe–Si–B amorphous ribbons

Systematic measurements of giant magneto-impedance (GMI) and its relaxation (magneto-impedance aftereffect) have been carried out in a series of Co-rich amorphous ribbons ranging in magnetostriction values from $\text{−3.5}$ to $\text{+3.5\hspace{0.17em}}\mathrm{ppm}.$ The value of GMI is a maximum for the alloy with the lowest value of magnetostriction, corresponding to a maximum of the transverse permeability. The impedance relaxation between two fixed times depends on the magnetostriction constant ${\mathrm{(\lambda }}_s)$ of the samples, and the observed trend is consistent with the theories which predict a direct relationship of the conventional permeability aftereffect (MAE) with the square of ${\lambda }_s.$ Furthermore, the variation of the impedance aftereffect with the driving current resembles the behavior of MAE, and a connection between both effects can be established.