The effect of elastic stresses on super-high-frequency magnetic impedance of amorphous magnetic microwires (original) (raw)
Journal of Applied Physics, 2013
We report the results of a detailed study of the effects of tensile and torsional stresses on the giant magnetoimpedance (GMI) characteristics of vanishing-magnetostrictive Co-rich microwires at microwave frequency. A complex stress-induced hysteresis behaviour is identified in the GMI response in the presence of tensile and torsional stresses. It is also revealed that there exists a competition between these two kinds of stresses on the critical field via the interactions with the intrinsic anisotropy. An "enhanced core-shell" model is proposed here to resolve the physical origin of the low-field hysteresis and the dependence of induced anisotropy field on the applied tensile and/or torsional stress. Our results are of both technical importance to the design of non-contact stress sensors exploiting the GMI of microwires and fundamental significance to the understanding of the microwave GMI characteristics of soft magnetic microwires in the presence of external stresses. V C 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798278\]
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.
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. ...
Giant magneto-impedance effect in CoMnSiB amorphous microwires
Journal of Magnetism and Magnetic Materials, 2001
The giant magneto-impedance (GMI) ratio, DZ=Z ¼ ½ðZðHÞ À ZðH max Þ=ZðH max Þ; in a nearly zero magnetostrictive Co 68.5 Mn 6.5 Si 10 B 15 amorphous microwire has been investigated for the frequency range 0.5-10 MHz, driving current amplitude of 0.5-2.5 mA, bias DC magnetic field up to 2400 A/m and under applied tensile stress up to 132 MPa. A maximum relative change in the GMI ratio up to around 130% is observed at a frequency of 10 MHz, magnetic DC field of about 180 A/m, driving current amplitude of 1 mA and under tension of 60 MPa. The tensile stress dependence of the magnetic field, H m ; corresponding to the maximum DZ=Z ratio allows to estimate the magnetostriction constant (l s E À 2  10 À7 ) to be in good agreement with l s values estimated by different methods and in amorphous alloys with similar compositions. r
Low-field hysteresis in the magnetoimpedance of amorphous microwires
Physical Review B, 2010
The phenomena of low-field hysteresis of the magnetoimpedance ͑MI͒ in zero-magnetostrictive amorphous wires are studied theoretically and experimentally. We developed a mathematical model for magnetization reversal and impedance field dependence. The presented model considers the low-field hysteresis and the effect of circular bias magnetic field. It is demonstrated that the hysteresis originates from a nonzero angle ␣ between the anisotropy easy axis and transversal plane. The bias field, which is produced by current running through the wire, considerably affects the MI dependence making it anhysteretic and highly asymmetric. The validity of the model is confirmed by the experiments. The main characteristics of the studied amorphous wire such as anisotropy field H A , angle between the anisotropy easy axis with the transversal direction ␣, and Gilbert damping constant ␣ G were obtained from the experiment in accordance with the presented model.
Journal of Applied Physics, 2003
The effect of conventional ͑CA͒ and stress annealing ͑SA͒ on magnetic properties of Fe 74 B 13 Si 11 C 2 glass-coated microwires has been studied. CA treatment does not significantly change the character of the hysteresis loop. Under certain annealing conditions ͑annealing temperature, T ann Ͼ300°C, applied stress, Ͼ700 MPa) rectangular hysteresis loop transforms into the inclined with magnetic anisotropy field above 1000 A/m. Such phenomenology has been related to the induction of transverse magnetic anisotropy by SA treatment. Under tensile stress the SA annealed microwire recovers rectangular hysteresis loop. Samples subjected to stress annealing show noticeable magnetoimpedance and stress impedance effects in spite of their large magnetostriction.
Applied Sciences, 2020
Stress-annealing enabled a considerable improvement in the GMI effect in both Fe- and Co-rich glass-coated microwires. Additionally, a remarkable magnetic softening can be achieved in stress-annealed Fe-rich microwires. Observed stress-annealing induced magnetic anisotropy is affected by annealing conditions (temperatures and stresses applied during annealing). The highest GMI ratio up to 310% was obtained in stress-annealed Co-rich microwires, although they presented rectangular hysteresis loops. A remarkable magnetic softness and improved GMI ratio over a wide frequency range were obtained in stress-annealed Fe-rich microwires. Irregular magnetic field dependence observed for some stress-annealing conditions is attributed to the contribution of both the inner axially magnetized core and outer shell, with transverse magnetic anisotropy.
Giant magnetoimpedance in thin amorphous and nanocrystalline microwires
Applied Physics A, 2014
We present the results on Giant magneto-impedance effect (GMI) in amorphous and nanocrystalline microwires at frequencies until 4 GHz, paying special attention to tailoring the frequency and magnetic field dependence of the GMI effect. Correlation between magnetoelastic anisotropy and magnetic field dependences of diagonal and off-diagonal impedance components are observed.