Stress-induced magnetic hysteresis in amorphous microwires probed by microwave giant magnetoimpedance measurements (original) (raw)
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Stress-induced magnetic hysteresis in amorphous microwires probed by microwave GMI measurements
The importance of amorphous microwires has grown dramatically over recent decades due to strong scientific 1,2 and application interest3-4. In the present work, we concentrate on a complex stress-induced hysteretic behavior identified in the GMI response for zero-magnetostrictive amorphous microwires at low magnetic fields, which has not yet been fully understood5. Based on both the experimental and theoretical results, we purpose to resolve the physical origin of the low-field hysteresis and its dependence on the applied tensile and/or torsional stress. Our results are of particular importance to the design of stress sensors exploiting the GMI of microwires. Experimentally, we measured the microwave (8-12 GHz) GMI of the glasscovered Co-rich microwires with the applied tensile stresses ranging from 0 to 900 MPa and the torsional stresses with a range of the torsional angles up to 13 �/m.6,7 The microwave GMI response of the untwisted wire has been found to exhibit the form of a sin...
Nanomaterials, 2021
Magnetoimpedance (MI) in Co-based microwires with an amorphous and partially crystalline state was investigated at elevated frequencies (up to several GHz), with particular attention paid to the influence of tensile stress on the MI behavior, which is called stress-MI. Two mechanisms of MI sensitivity related to the DC magnetization re-orientation and AC permeability dispersion were discussed. Remarkable sensitivity of impedance changes with respect to applied tensile stress at GHz frequencies was obtained in partially crystalline wires subjected to current annealing. Increasing the annealing current enhanced the axial easy anisotropy of a magnetoelastic origin, which made it possible to increase the frequency of large stress-MI: for 90mA-annealed wire, the impedance at 2 GHz increased by about 300% when a stress of 450 MPa was applied. Potential applications included sensing elements in stretchable substrates for flexible electronics, wireless sensors, and tunable smart materials. ...
Technical Physics Letters, 2012
It has been demonstrated experimentally that, in magnetic microwires with a negative sign of the magnetostrictive constant, imposing an axial stress results in an increase of the effective field of circular anisotropy. Torsion stresses form a helical magnetic structure that yields hysteresis and irreversible jumps on giant magnetic impedance curves. The field at which the stability of a magnetic system deteriorates depends on the values of axial and torsion stresses.
physica status solidi (a), 2002
The effect of external (torsion and tensile) stresses on the electrical impedance of nearly-zero magnetostrictive amorphous microwires (conventional and glass covered) is reported. Glass coated Co 68.5 Mn 6.5 Si 10 B 15 microwire exhibits a maximum relative change in magnetoimpedance ratio up to around 130% at a frequency of 10 MHz, magnetic dc field of about 180 A/m and under tension of 60 MPa. This giant magnetoimpedance (GMI) effect of the microwire is affected by the magnetoelastic anisotropy induced in the sample by applying tensile stress. In addition, from the linear variations of the magnetic field H m corresponding to the maximum DZ/Z ratio, with the applied tensile stress, that is the H m (s) curve, the magnetostriction constant of this amorphous microwire (l s % --2 Â 10 --7 ) is estimated. The torsion giant impedance (TGI) ratio (DZ/Z) x has been investigated in as-cast and annealed (Co 0.94 Fe 0.06 ) 72.5 B 15 Si 12.5 conventional amorphous microwire.
Magnetism, 2023
It was observed recently that the giant magnetoimpedance (GMI) effect in Fe-rich glass-coated amorphous microwires with positive magnetostriction can be improved significantly by means of post-annealing. The increase in the GMI is attributed to the induced helical magnetic anisotropy in the surface layer of the microwire, which appears after the annealing. The application of external stresses to the microwire may result in changes in its magnetic structure and affect the GMI response. In this work, we study theoretically the influence of the tensile and torsional stresses on the off-diagonal magnetoimpedance in annealed amorphous microwires with positive magnetostriction. The static magnetization distribution is analyzed in terms of the core–shell magnetic structure. The surface impedance tensor is obtained taking into account the magnetoelastic anisotropy induced by the external stresses. It is shown that the off-diagonal magnetoimpedance response exhibits strong sensitivity to the magnitude of the applied stress. The obtained results may be useful for sensor applications of amorphous microwires.
IEEE Transactions on Magnetics, 2008
Surface magnetization reversal of Co-rich amorphous glass covered microwires in the presence of torsion stress has been studied by magneto-optical Kerr effect. The dependence of the angle of the helical anisotropy on the applied torsion stress has been obtained for the first time based on the analysis of the magneto-optical experimental results. The value of the limit angle of the torsion stress induced helical anisotropy has been found.
Journal of Alloys and Compounds, 2018
The influence of stress-annealing on the magnetic softness and the magnetoimpedance effect of Fe-and Co-based glass-coated microwires is studied. As-prepared Co-rich glass-coated microwires present better magnetic softness and rather higher magnetoimpedance ratio with a double-peak dependence, typical for materials with transverse magnetic anisotropy. As-prepared Fe-based microwires present a rectangular hysteresis loop with a coercivity an order of magnitude higher and a magnetoimpedance ratio of an order of magnitude lower. Stress-annealing of Co-and Fe-based glass-coated microwire allows considerable magnetoimpedance ratio increasing. The impact of stress-annealing is especially pronounced in a Fe-based microwire, where transverse magnetic anisotropy, large (an order of magnitude) improvement of the magnetic softness and magnetoimpedance ratio are observed. In Co-based microwire a magnetoimpedance ratio improvement for short annealing time and a change of hysteresis loop from linear to rectangular are observed. Observed stress-induced anisotropy and related changes of magnetic properties are discussed considering internal stresses relaxation and "backstresses". Obtained experimental results yield new and important insights into the influence of stress-induced magnetic anisotropy on the magnetoimpedance effect and hysteresis loops of glass-coated microwires.
Giant magnetoimpedance effect in a positive magnetostrictive glass-coated amorphous microwire
Physical Review B, 2002
The giant magnetoimpedance ͑GMI͒ effect in positive magnetostrictive glass-coated amorphous Co 83.2 Mn 7.6 Si 5.8 B 3.3 microwire has been studied as a function of a dc magnetic field Ϫ140ϽH dc Ͻ140 Oe and frequency 0.1Ͻ f Ͻ12.85 MHz. A maximum change of 43% in the MI of the as-quenched sample has been observed around 5 MHz frequency. Heat treatment of the sample by passing a dc current of 50 mA through it enhances the MI value to a large extent ͑maximum change ϳ94%͒ by increasing the outer domain volume and inducing a transverse anisotropy. On the other hand, application of an external tensile stress reduces the GMI value by increasing the inner core domain and developing an axial anisotropy. In an as-quenched sample, the maximum value of MI is observed at H dc ϳ0 when measured at frequency f Ͻ8 MHz beyond which a two peak MI profile is seen. The heat-treated sample shows this two peak behavior from a much lower frequency ͑below 1 MHz͒ and additional peaks at H dc ϳ0 for f Ͼ10 MHz. Asymmetry in the MI peaks of a microwire has been produced by passing a dc current through the sample during impedance measurement. The magnetization of the as-quenched and heat-treated samples has also been studied to understand the domain structure and magnetoimpedance results.