Giant magneto impedance effect of Co-rich amorphous fibers under magnetic interaction

The quasi-metallic fibers were selected from 1 to 40 pieces and connected in parallel in this study. The giant magneto impedance (GMI) effect of Co-based melt extract fibers in the bundle mode was investigated, and the distribution of the surface circumferential magnetic field on the fibers was also analyzed. Such distribution was induced by the driving current, which gave rise to the circular magnetization process and the GMI effect. The improved GMI effect with much higher field sensitivity was observed in these fiber bundles. Results show that the field sensitivities of the four-fiber and six-fiber bundles reach 19.5 V·m·kA−1 (at 1 MHz) and 30.8 V·m·kA−1 (at 5 MHz). The circumferential magnetic field distributed throughout the fiber’s circumferential surface is rearranged and becomes uneven due to the magnetic interaction among fibers. There are both strengthened and weakened magnetic field parts around these fibers’ surfaces. The strengthened magnetic field improves the circumferential domain magnetization of the surface, resulting in larger GMI effects. However, the weakened parts inhibit the circumferential magnetization process and, therefore, the GMI effect. This also induces greater magnetization damp because of the increased domain interactions under the strong skin effect. The co-effect between the magnetic domains and the circumferential magnetization induces the optimization of the GMI effect in the four-fiber bundles. The observed GMI effect proves that fibers in bundle form can modify the sensitivity of the GMI effect. Moreover, different fiber bundles could be tuned according to the working conditions in order to manipulate the GMI response.