Influence of magnetostriction constant on magnetoimpedance–frequency dependence

Value and sign influence of magnetostriction constant, λs, on magnetoimpedance (MI)–frequency dependence is evaluated for frequencies up to 30 MHz. For this goal, samples with positive (Fe77.5Si7.5B15), negative (Co72.5Si12.5B15) and nearly zero (Co68.15Fe4.35Si12.5B15) magnetostriction constant are used. Differences on MI maximum ratios above two orders of magnitude are achieved among samples with positive and negative magnetostriction constant. In the case of Co68.15Fe4.35Si12.5B15 sample, MI ratios above 1000% are obtained. These values of MI ratio are higher than usual values reported in the bibliography for this composition. In order to explain this feature, the internal magnetic structure of the amorphous wires has been taken into account.