Asymmetrical magnetoimpedance in as-cast CoFeSiB amorphous wires due to ac bias

Makhnovskiy, D. P.; Панина, Л. В.; Mapps, D.J.

doi:10.1063/1.126896

Cited by 62 publications

(38 citation statements)

References 7 publications

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“…Another method of producing the asymmetric GMI profile consists of applying an axial ac bias field to a sample. 5 In this case, the asymmetry results from the mixing of the diagonal and off-diagonal components of the impedance tensor due to the ac cross-magnetization process. 1 The third type of the asymmetric GMI has been observed in Co-based amorphous ribbons annealed in air in the presence of a weak magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

Buznikov

Kim

et al. 2005

Journal of Applied Physics

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The off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons was measured in the low-frequency range using a pickup coil wound around the sample. The asymmetric two-peak behavior of the field dependence of the off-diagonal impedance was observed. The asymmetry is attributed to the formation of a hard magnetic crystalline phase at the ribbon surface. The experimental results are interpreted in terms of the surface impedance tensor. It is assumed that the ribbon consists of an inner amorphous region and surface crystalline layers. The coupling between the crystalline and amorphous phases is described through an effective bias field. A qualitative agreement between the calculated dependences and experimental data is demonstrated. The results obtained may be useful for development of weak magnetic-field sensors.

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Section: Introductionmentioning

confidence: 99%

Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

Buznikov

Kim

et al. 2005

Journal of Applied Physics

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“…6,8 Since the discovery of the effect, MI has been studied in a wide variety of systems, e. g., sheets, 9 wires, [10][11][12][13][14][15][16][17][18] ribbons, [19][20][21][22][23][24] and thin films. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] In the particular case of films, an increasing interest has been devoted to the effect in single layered, 25,26 multilayered, [27][28][29][30][31][32] and structured multilayered thin films, 30,31,[33][34][35][36][37][38][39] since...…”

Section: Introductionmentioning

confidence: 99%

Magnetization dynamics in nanostructures with weak/strong anisotropy

Andrade

Corrêa

Viegas

et al. 2014

Journal of Applied Physics

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We investigate the high-frequency response of magnetization dynamics through magnetoimpedance (MI) effect in Permalloy-based multilayered thin films produced with two different non-magnetic metallic spacers: Cu and Ag. Due to the nature of the spacer materials, we are able to play with magnetic properties and to study both systems with weak/strong magnetic anisotropy. We verify very rich features in the magnetoimpedance behavior and high magnetoimpedance ratios, with values above 200%. We compare the MI results obtained in multilayered thin films with distinct spacers and number of bilayers, and discuss them in terms of the different mechanisms that govern the MI changes observed at distinct frequency ranges, intensity of the magnetic anisotropy, alignment between dc magnetic field and anisotropy direction. Besides, by considering a theoretical approach that takes into account two single models together and calculate the transverse magnetic permeability and the MI effect, we support our interpretation via numerical calculations modeling the effect of weak/strong magnetic anisotropy on the MI response. Thus, we confirm that these features are very important for the use of multilayered films in sensor applications and, both the frequency and field response can be tailored to fulfill the requirements of a given device.

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“…However, it has been noticed that certain conditions favor the emergence of an asymmetry in those curves, denominated Asymmetric Giant Magnetoimpedance, or AGMI effect, characterized by an increase of one of the peaks, or valleys, with a decrease of the other, in the |Z|xH curves. In spite of the fact that not all causes of AGMI are well known, three factors are highlighted in the literature: a) asymmetry due to DC current; b) asymmetry due to AC magnetic field and c) asymmetry due to "exchange bias" (Kim et al, 1999;Machado et al, 1999;Makhnovskiy et al, 2000). As presented in the subsequent sections, on the present study the AGMI effect was induced by overlapping a DC biasing current to the alternating current (AC) used in the GMI measurements.…”

Section: Agmi Effectmentioning

confidence: 91%

Sensitivity improvement of GMI magnetic and pressure transducers for biomedical measurements

Silva¹,

Gusmão²,

Barbosa

et al. 2011

RBEB

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This work presents an experimental study aiming the sensitivity optimization of Giant Magnetoimpedance (GMI) sensors, by means of properly choosing the values of their conditioning parameters. The optimized GMI sensors, together with the development of improved transduction electronic circuits, can lead to the sensitivity enhancement of GMI biomedical, pressure and magnetic transducer prototypes, previously developed by the research group at LaBioMet, PUC-Rio. Those prototypes are, respectively, aimed at the measurement of arterial pulse waves and the localization of magnetic foreign bodies inserted in the human body. Thus, the experimental characterization of GMI ribbon-shaped samples (Co 70 Fe 5 Si 15 B 10 ) was performed, as a function of the external magnetic field, including the experimental evaluation of the asymmetric GMI effect (AGMI). The parameters that affect the behavior of the GMI samples were experimentally analyzed, such as the DC level (0 mA to 100 mA) and frequency (100 kHz to 10 MHz) of the excitation current, as well as the samples length (1 cm, 3 cm, 5 cm and 15 cm). The conditioning parameters, experimentally identified, that optimize the GMI samples sensitivity lead to a maximum specific sensitivity of 0.84(8400 Ω ·T -1 ·cm -1 ). A new electronic circuit was developed for conditioning and reading of the GMI samples, which directly contributed to the performance enhancement of both transducers. The electronic circuits developed were evaluated supposing the operation of the GMI samples in their most sensitive region. Comparing to previously developed prototypes, the optimum sensitivity achieved for the new configuration of the GMI magnetic transducer increased about 9 times (from 0.12 mV/nT to 1.08 mV/nT), and the sensitivity of the modified pressure transducer increased approximately 7 times (from 1 mV/Pa to 7 mV/Pa). Keywords

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Asymmetrical magnetoimpedance in as-cast CoFeSiB amorphous wires due to ac bias

Cited by 62 publications

References 7 publications

Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

Off-diagonal magnetoimpedance in field-annealed Co-based amorphous ribbons

Magnetization dynamics in nanostructures with weak/strong anisotropy

Sensitivity improvement of GMI magnetic and pressure transducers for biomedical measurements

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