Giant magnetoimpedance modelling using Fourier analysis in soft magnetic amorphous wires

In this work, the Fourier analysis is employed to investigate the giant mag netoimpedance (GMI) effect in a FeCoSiB amorphous wire with vanishing magne tostriction In order to modify the initial quenched-in anisotropy, pieces 8 cm in length were submitted to Joule heating treatments below the correspo nding Curie point. The induced circumferential anisotropy determines the fi eld evolution of the electrical impedance of the sample upon the applicatio n of an axial magnetic field. The experimental results are interpreted with in the framework of the classical electrodynamical theory where a simple ro tational model is used to estimate the circular magnetization process of th e sample. The mean value or the circumferential permeability is obtained th rough Fourier analysis of the time derivative of the estimated circular mag netization. Moreover, the existence of a second harmonic component of the G MI voltage is also experimentally detected. Its amplitude sensitively evolv es with the axial DC magnetic field and its appearance is associated to an asymmetry in the circular magnetization process. (C) 2001 Elsevier Science B.V. All rights reserved.