Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

TL;DR

This study investigates the off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons, revealing asymmetric behavior due to surface crystalline phases, with implications for developing sensitive magnetic-field sensors.

Contribution

It introduces a model combining surface crystalline phases and amorphous regions to explain off-diagonal magnetoimpedance asymmetry in field-annealed ribbons.

Findings

Asymmetric two-peak behavior observed in off-diagonal impedance.

Surface crystalline phases cause the observed asymmetry.

Qualitative agreement between model calculations and experimental data.

Abstract

The off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons was measured in the low-frequency range using a pick-up coil wound around the sample. The asymmetric two-peak behavior of the field dependence of the off-diagonal impedance was observed. The asymmetry is attributed to the formation of a hard magnetic crystalline phase at the ribbon surface. The experimental results are interpreted in terms of the surface impedance tensor. It is assumed that the ribbon consists of an inner amorphous region and surface crystalline layers. The coupling between the crystalline and amorphous phases is described through an effective bias field. A qualitative agreement between the calculated dependences and experimental data is demonstrated. The results obtained may be useful for development of weak magnetic-field sensors.