Influence of Various Heat Treatments on Giant Magnetoimpedance Effect in Nanocrystalline FeSiBNbCu Ribbons

Abstract

In this paper we present studies on the frequency dependence of the magneto-impedance in the range of 0.1–2 MHz for Fe73.5Si13.5B9Nb3Cu1 and Fe73.5Si16.5B6Nb3Cu1 nanocrystalline ribbons, which differ in the sign of the magnetostriction constant. As cast samples were annealed in Ar atmosphere at 560℃, with and without an DC and AC magnetic field. At a fixed frequency, an improvement in the field annealed 13.5% Si samples, when compared with the zero field annealed ones, can be observed. On the 16.5% Si field annealed samples only a reduction of magneto-impedance ratio could be observed, when compared to the non-field annealed ones. Analysis of the magnetic properties and X-ray data shows that the observed changes in magneto-impedance effect are consequence of the induced magnetic anisotropy.