Effect of Ni content on the crystallization, soft magnetic properties and GMI effect in amorphous Co<inf>68</inf>Fe<inf>7−x</inf>Ni<inf>x</inf>Si<inf>15</inf>B<inf>10</inf> (x = 0, 1.5, 3, 4.5) ribbons

Abstract

Soft ferromagnetic amorphous ribbons are widely used for a wide range of applications, including high-frequency transformers and magnetic sensors. The recent discovery of a so-called giant mag-netoimpedance (GMI) effect in these alloys has made them very attractive candidates for making highly sensitive magnetic sensors [1]. GMI effects have been reported in Co-based amorphous ribbons owing to the high transverse permeability, due to the presence of a transversely oriented domain configuration [1]. Like Co-based amorphous wires, ribbons with CoFeSiB composition and nearly zero but negative magnetostriction, were found to show the largest GMI ratio among Co-based ribbons [2]. The GMI ratio reached a value as high as 160% at a frequency of 1 MHz in the (Co 1−x Fe x ) 70 Si 12 B 18 (x = 0.057) amorphous ribbon with nearly zero magnetostriction. The research on GMI effect sensors is now focused on the material composition and structure of sensitive components [3]. In this presentation, we attempt to improve the GMI ratio of amorphous Co 68 Fe 7 Si 15 B 10 alloy ribbons by introducing Ni element.