Stress effect on magnetoimpedance in amorphous wires at gigahertz frequencies and application to stress-tunable microwave composite materials

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. a)

Stress-dependent magnetoimpedance in Co-based amorphous wires and application to tunable microwave composites

“…However, the theoretical and experimental analysis conducted in [4][5][6][7] has shown that eff  changes very little with both the external axial magnetic field ex H and anisotropy field K H for frequencies much higher than the ferromagnetic resonance, although preserving its relatively high values (in the range of tens). Therefore, the dependence of the magnetoimpedance on various external factors such as a dc magnetic field or stress (which changes K H ) will be entirely determined by the static magnetization angle  .…”

“…This effect has been proposed to be used as a stress-sensing mechanism in the composite structures. [5,6] In this paper, we have investigated the MI effect in CoMnSiB glass-coated amorphous wires with thermally induced nearaxial anisotropy. This wire shows a dc magnetization process which is dependent on a tensile stress, changing from almost a rectangular loop without a stress to a linear one when a strong stress is applied.…”

“…The use of ferromagnetic wires as filling elements in a dielectric matrix  makes it possible to achieve a large adjustability of the effective electromagnetic response. [3][4][5][6] These composites might have a particular interest for remote nondestructive testing, when the stress distribution inside the composite structure or on its surface can be visualized in the microwave range. In this work, the composite structure with short wires has been considered, which demonstrates the Lorentz dipole dispersion of eff  .…”

Effect of the metal-to-wire ratio on the high-frequency magnetoimpedance of glass-coated CoFeBSi amorphous microwires

“…Since glass exerts some mechanical stress on the metallic wire, a change in the magnetic response is expected; other works have rather investigated the effect of external stress [9,10], as well as that of various annealing methods [11,12]. Consequently, it is of interest to finely tune the physical properties through the control of the thickness and nature of the glass sheath.…”

Stress and field contactless sensor based on the scattering of electromagnetic waves by a single ferromagnetic microwire

“…While the metallic core provides the magnetic behavior, the cover has a protective and stress-inducting function. Due to its tiny dimensions and its particular effects like Giant Magnetoimpedance (GMI), [8][9][10][11][12][13][14] bistability, 15 ferromagnetic resonance, 16 and magnetoelastic resonance, these materials have been considered as promising sensor elements. Furthermore, since the metallic core is covered by a biocompatible Pyrex shell, they are suitable for biological and medical applications.…”