Helical anisotropy and magnetoimpedance of CoFeSiB wires under torsional stress

TL;DR

This paper investigates how torsional stress affects the magnetoimpedance and anisotropy in CoFeSiB wires, using a simple model to interpret experimental asymmetries and extract physical parameters.

Contribution

It introduces a model explaining the anisotropy behavior under torsion, supported by experimental data, advancing understanding of stress-induced magnetic effects in wires.

Findings

The model accurately describes the anisotropy field versus magnetic field.

Experimental data show asymmetry in magnetoimpedance with torsion angle.

Physical parameters of the wire are extracted from the model.

Abstract

Recent measurements of the magnetoimpedance (at a fixed frequency of 1 MHz) of cobalt-rich wires subjected to torsion stress show an asymmetry as a function of torsion angle stemming from residual anisotropies induced during wire fabrication. We interpret these measurements with a simple model based on the competition between a circumferential magnetic anisotropy and another one induced by torsional and residual stress. This allows extraction of the physical parameters of the wire and explains the positive and negative torsion cases. The agreement between theoretical and experimental results provides a firm support for the model describing the behaviour of the anisotropy field versus static magnetic field for all torsion angles.