Influence of an ac magnetic field and induced magnetic anisotropy on the surface magnetoimpedance tensor in an amorphous wire

Chen, A P; Zhukova, V.; Zhukov, A.; Domínguez, L.; Chizhik, A.; Blanco, J.M.; González, J.

doi:10.1088/0022-3727/37/20/001

“…Considerable attention have been given to describe the MI effect in samples presenting cylindrical geometry with distinct anisotropy configurations [44][45][46][47] . For this case, e. g., Makhnovskiy et al 45 have reported a very strict study on the surface impedance tensor, in which theoretical results for the cylindrical geometry are directly compared to experimental measurements acquired for ferromagnetic wires.…”

Section: Introductionmentioning

confidence: 99%

Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

Corrêa

¹

,

Bohn

²

,

Silva

³

et al. 2014

Journal of Applied Physics

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The magnetoimpedance effect is a versatile tool to investigate ferromagnetic materials, revealing aspects on the fundamental physics associated to magnetization dynamics, broadband magnetic properties, important issues for current and emerging technological applications for magnetic sensors, as well as insights on ferromagnetic resonance effect at non-saturated magnetic states. Here, we perform a theoretical and experimental investigation of the magnetoimpedance effect for the thin film geometry in a wide frequency range. We calculate the longitudinal magnetoimpedance for single layered, multilayered or exchange biased systems from an approach that considers a magnetic permeability model for planar geometry and the appropriate magnetic free energy density for each structure. From numerical calculations and experimental results found in literature, we analyze the magnetoimpedance behavior, and discuss the main features and advantages of each structure. To test the robustness of the approach, we directly compare theoretical results with experimental magnetoimpedance measurements obtained in a wide range of frequencies for an exchange biased multilayered film. Thus, we provide experimental evidence to confirm the validity of the theoretical approach employed to describe the magnetoimpedance in ferromagnetic films, revealed by the good agreement between numerical calculations and experimental results.

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“…Under the same conditions the ends of the wire sample were clamped to allow a simultaneous application of a torsion stress of π/4 rad cm −1 . This treatment modifies the circularly magnetized sheath of the sample, developing a helically magnetized surface layer [18][19][20]. Although this helical anisotropy is not uniform along the wire radius, we can consider it roughly uniform at high enough frequencies because in this case the current flows in a thin surface layer.…”

Section: Experimental Measurementsmentioning

confidence: 99%

“…This induced anisotropy obviously affects the GMI response. Also, quite recently, we have reported in [20] experimental results on the effect of the helical anisotropy on the GMI effect. Such anisotropy was induced by a torsion annealing treatment.…”

Section: Introductionmentioning

confidence: 96%

“…As is well known, the magnetic anisotropy in soft amorphous wires is mainly of a magnetoelastic character, arising from the internal stresses caused by the heat transfer during the fabrication process. Therefore, the GMI effect is very sensitive to applied tensile 0022-3727/06/091718+06$30.00 © 2006 IOP Publishing Ltd Printed in the UK and torsional stresses [16][17][18][19][20], which makes these materials suitable for use as sensing elements. In addition, magnetic anisotropy can be induced in these amorphous wires by thermal treatment under a tensile or torsion stress.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the ac magnetic field frequency on the magnetoimpedance of amorphous wire

Chen¹,

García²,

Zhukov³

et al. 2006

J. Phys. D: Appl. Phys.

Self Cite

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Experimental and theoretical studies on the influence of ac magnetic field frequency on the axial diagonal (ζzz) and off-diagonal (ζϕz) components of the magnetoimpedance (MI) tensor in (Co0.94Fe0.06)72.5Si12.5B15 amorphous wires have been performed. The frequency (f) of an ac current flowing along the wire was varied from 1 to 20 MHz with the current amplitude less than 15 mA. In order to enhance the ζϕz component, the amorphous wire was submitted to torsion annealing for developing and preserving a helical magnetic anisotropy in the surface of the wire. The experimental measurements show that the value of the impedance is proportional to the square-root of the ac current frequency, , in the vicinity of Hex < HK and this increase is due to the contribution of the resistance (real part of the impedance). The measurements also indicate that the peaks of the MI curve shift slightly towards higher field values with increasing f.In a theoretical study the magnetoimpedance expressions ζzz and ζϕz have been deduced using the Faraday law in combination with the solutions of the Maxwell and Landau–Lifshitz–Gilbert (LLG) equations. By analysing quantitatively the spectra of ζzz and ζϕz, the phenomenon of the shift in the peaks of the MI curve with f has been considered as a characteristic of the helical anisotropy in the domain structure of the wire surface.

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“…Since the system geometry has an important role on MI results, several studies have been performed to obtain further information on this dependence. Considerable attention have been given to describe the MI effect in samples presenting cylindrical geometry with distinct anisotropy configurations [44][45][46][47] . For this case, e. g., Makhnovskiy et al 45 have reported a very strict study on the surface impedance tensor, in which theoretical results for the cylindrical geometry are directly compared to experimental measurements acquired for ferromagnetic wires.…”

Section: Introductionmentioning

confidence: 99%

Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

Corrêa,

Bohn,

da Silva

et al. 2014

Preprint

0

View full text Add to dashboard Cite

The magnetoimpedance effect is a versatile tool to investigate ferromagnetic materials, revealing aspects on the fundamental physics associated to magnetization dynamics, broadband magnetic properties, important issues for current and emerging technological applications for magnetic sensors, as well as insights on ferromagnetic resonance effect at non-saturated magnetic states. Here, we perform a theoretical and experimental investigation of the magnetoimpedance effect for the thin film geometry in a wide frequency range. We calculate the longitudinal magnetoimpedance for single layered, multilayered or exchange biased systems from an approach that considers a magnetic permeability model for planar geometry and the appropriate magnetic free energy density for each structure. From numerical calculations and experimental results found in literature, we analyze the magnetoimpedance behavior, and discuss the main features and advantages of each structure. To test the robustness of the approach, we directly compare theoretical results with experimental magnetoimpedance measurements obtained in a wide range of frequencies for an exchange biased multilayered film. Thus, we provide experimental evidence to confirm the validity of the theoretical approach employed to describe the magnetoimpedance in ferromagnetic films, revealed by the good agreement between numerical calculations and experimental results.

show abstract

Influence of an ac magnetic field and induced magnetic anisotropy on the surface magnetoimpedance tensor in an amorphous wire

Cited by 3 publications

References 29 publications

Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

Influence of the ac magnetic field frequency on the magnetoimpedance of amorphous wire

Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment

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