Low-field microwave magnetoimpedance in amorphous microwires

Abstract

We have measured the low-field (<40 Oe) microwave losses in 5 μm diam glass-covered amorphous wires fabricated by the Taylor–Ulitovsky method at 9.8 and 32.5 GHz and their hysteresis loops at very low frequency (0.1 Hz). They exhibit well-differentiated hysteresis loops depending on the magnetostrictive character of the alloy compositions [positive (FeSiBC), vanishing (CoMnSiB), and negative (CoSiB) magnetostriction] as a consequence of the particular magnetoelastic anisotropy distribution and hence the spontaneous domain structure. In the low-field region for which the microwires are not magnetically saturated, as is typical in ferromagnetic resonance experiments, the microwave losses evolve with applied field in a similar manner to that of the magnetization process, and denote a correlation between microwave losses and the magnetization process of magnetically nonsaturated samples.

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

“…Such a functional dependence is referred to as "valve-like" behavior of MI at microwaves. Previously, this effect has been also observed experimentally in [8,9] In amorphous ferromagnetic alloys, the preferable magnetization direction is set by the combined effect of the shape anisotropy and the magnetoelastic anisotropy arising from the coupling between magnetostriction  and internal stresses   (axial, radial, and azimuth). The stresses are induced during the fabrication process and can be controlled by further post production treatment like drawing and annealing.…”

Liquid pressure wireless sensor based on magnetostrictive microwires for applications in cardiovascular localized diagnostic

“…[8][9][10] 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), [11][12][13][14][15][16][17] bistability, 18 ferromagnetic resonance 19 and magnetoelasticity, 20 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.…”

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.…”

“…18,19 In this context, Co rich amorphous alloys with low magnetostriction have been found to exhibit outstanding GMI effect. 9 There is much literature regarding microwave related applications of microwires or microwire-based materials. [20][21][22][23][24] Some of these articles have nicely shown how different arrangements of microwires forming arrays or embedded in different types of matrixes may be used for enhancing their sensitivity as GMI elements.…”

“…We selected this composition because, as stated above, Co rich microwires are well known to exhibit a noticeable high GMI effect. 9 Due to its amorphous structure, even though they exhibit low or moderate magnetostriction are high sensitive magnetoelastic elements for detecting applied stresses as thoroughly discussed elsewhere since longtime ago. 25 Both antennas were connected to a two port AGILENT E8362B Network Analyzer.…”