The sensitive magnetoimpedance effect in Fe-based soft ferromagnetic ribbons

A comprehensive analysis of magnetoimpedance (MI) phenomena in Fe-based nanocrystalline ribbons is presented in this paper. Giant MI responses have been observed in nanocrystalline samples annealed over the temperature 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 the 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 held 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.