Peculiar behavior of the magneto-impedance in Fe-based amorphous wires under torsion

The inductive (omegaL) and resistive (R) components of the impedance of an amorphous wire (Fe77.5Si7.5B15) subjected to torsional stresses are measure d. For a critical value of the AC driving current L abruptly increases due to irreversible magnetization processes in the circumferential configuratio n. Suitable combinations of the AC driving current amplitude and frequency give rise to a peak in the resistive variations and a minimum in the induct ance. The inductance shows a bistable asymmetric hysteresis loop (L vs. H). The torsional stress increases the coercivity of the longitudinal hysteres is loop of the wire but favors the reaching of the saturation magnetization at lower fields. (C) 2000 Elsevier Science B.V. All rights reserved.