Influence of induced anisotropy and magnetostriction on the giant magnetoimpedance effect and its aftereffect in soft magnetic amorphous ribbons

Systematic measurements of giant magnetoimpedance (GMI) and its relaxation (magnetoimpedance aftereffect, MIAE) have been carried out on a series of Go-rich amorphous ribbons with different magnetostriction constant, before and after the induction of transverse anisotropy through stress-annealing. Interesting characteristics of the GMI effect as a function of driving current (circular field) amplitude and frequency were observed. The applied thermal treatment produced a shift in the magnetostriction values, as well as a strong magnetic anisotropy perpendicular to the ribbons axis. The behaviour of GMI changes drastically upon stress-annealing, all samples displaying a hysteretic behaviour and a well-defined peak structure. However, the magnitude of the effect is not substantially affected by the thermal treatment. On the other hand, a strong suppression of the impedance relaxation (aftereffect) is verified after the annealing procedure. Besides the obvious technical implications, the experimental data are used to discuss the possible physical origin of the magnetoimpedance aftereffect. (C) 1999 Elsevier Science B.V. All rights reserved.