THE SENSITIVE MAGNETOIMPEDANCE EFFECT IN FE-BASED SOFT FERROMAGNETIC RIBBONS

A comprehensive analysis of magnetoimpedance (MI) phenomena in Fe-base d nanocrystalline ribbons is presented in this paper. Giant MI respons es have been observed in nanocrystalline samples annealed over the tem perature range 490 and 600 degrees C. More than 400% increases of the MI ratio were obtained both in Fe73.5CuNb3Si13.5B9 and in Fe88Zr7B4Cu ribbons. The sensitivity can reach a value larger than 60% Oe(-1) in t he field range 3-7.2 Oe at 800 kHz for Fe73.5CuNb3Si13.5B9 ribbons. No Mi effect was observed in an as-quenched amorphous Fe88Zr7B4Cu sample , because of its very low permeability. A mostly resistive feature was found in an as-quenched amorphous Fe73.5CuNb3Si13.5B9 sample. The hel d dependences of the effective permeability show a typical transverse anisotropy property, and the development of the transverse anisotropy in naturally annealed Fe-based ribbons was analysed.