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 Fe_73.5Si_13.5B₉Nb₃Cu₁ and Fe_73.5Si_16.5B₆Nb₃Cu₁ 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.