Giant magnetoimpedance and field sensitivity in amorphous and nanocrystalline (Co1−xFex)89Zr7B4 (x = 0, 0.025, 0.05, 0.1) ribbons

We report on the giant magnetoimpedance (GMI) effect and its field sensitivity (η) in amorphous and nanocrystalline (Co_1−xFe_x)₈₉Zr₇B₄ ribbons with x = 0, 0.025, 0.05, and 0.10. The nanocrystalline samples were obtained by annealingamorphous ribbons in a field of 2 T applied perpendicular to the ribbon axis. We find that for the amorphous samples the GMI ratio tends to decrease with Fe doping, while the largest value of η is achieved for the x = 0.025 composition. For the nanocrystalline samples, the GMI ratio and η first decrease with increase of Fe-doped content from x = 0 to x = 0.05 and then increase for x = 0.1. The field annealing significantly enhances the GMI ratio and η in the nanocrystalline samples with x = 0 and 0.1, but decreases the η in the nanocrystalline samples with x = 0.025 and 0.05. The variations of the GMI ratio and the field-induced magnetic anisotropy field (H_K) upon Fe doping are correlated with the microstructural changes in the nanocrystalline samples.