Stress effect on magnetoimpedance (MI) in amorphous wires at GHz frequencies and application to stress-tunable microwave composite materials

TL;DR

This paper investigates how tensile stress affects magnetoimpedance in amorphous wires at microwave frequencies and explores their application in stress-tunable microwave composite materials for structural monitoring.

Contribution

It provides experimental and theoretical analysis of stress-induced MI changes at GHz frequencies and proposes their use in creating stress-sensitive microwave composites.

Findings

Large MI sensitivity to stress at GHz frequencies.

Theoretical model aligns with experimental results.

Potential for stress monitoring via microwave contrast imaging.

Abstract

The effect of tensile stress on magnetoimpedance (MI) in CoMnSiB amorphous wires at microwave frequencies (0.5-3 GHz) is investigated both experimentally and theoretically. In the presence of the dc bias magnetic field of the order of the anisotropy field, the impedance shows very large and sensitive change when the wire is subjected to a tensile stress: 100% and 60% per 180 MPa for frequencies 500 MHz and 2.5 GHz, respectively. It is demonstrated that this behavior owes mainly to the directional change in the equilibrium magnetization caused by the applied stress and field, which agrees well with the theoretical results for the surface impedance. This stress effect on MI is proposed to use for creating microwave stress-tunable composite materials containing short magnetic wires. The analysis of the dielectric response from such materials shows that depending on the stress level in the material, the dispersion of the effective permittivity can be of a resonant or relaxation type with a considerable change in its values (up to 100% at 600 MPa). This media can be used for structural stress monitoring by microwave contrast imaging.