Preparation and giant magneto-impedance behavior of Co-based amorphous wires

The giant magneto-impedance (GMI) in Co69.5Fe4.35Cr1Si8B17 microwires is studied. Wires with different diameter were fabricated by a modified glass-coated melt spinning technique, and then the glass was removed before the metallic nucleus was cold drawn. A transition from single-peak (SP) to double-peak (DP) GMI behavior was observed for the microwires after cold drawing. This could be explained by the induced circumferential stress during cold drawing, which changes the surface magnetic anisotropy of the wire from helical domains to circular domains. GMI ratio as well as field sensitivity were improved significantly after cold drawing, and that would be significant for application.