Asymmetrical Magneto-Impedance Effect in an Amorphous Wire with a Coil

Gunji, Toshihiro; Panina, L.V.; Mohri, K.

doi:10.3379/jmsjmag.21.793

Cited by 27 publications

(3 citation statements)

References 8 publications

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“…The coil gives an additional source of e.m.f which may cause the amplitude of the ac current to change during the experiment as well. 22,23…”

Section: B Circumferential Anisotropymentioning

confidence: 99%

“…Further experiments on MI have resulted in the discovery of such phenomena as asymmetrical or bi-stable MI in twisted (or torsion annealed) amorphous wires, [14][15][16][17][18] asymmetrical MI in annealed amorphous ribbons 19,20 and in films with crossed anisotropy, 21 and the effect of an ac bias field producing asymmetrical voltage response in systems having no magnetic asymmetry in the dc magnetic configuration. 22,23 Regarding these phenomena, the approach based on equations (1),(2) can fail to provide even a qualitative explanation, especially in the case of the ac biased asymmetrical MI.…”

Section: Introductionmentioning

confidence: 99%

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Field-dependent surface impedance tensor in amorphous wires with two types of magnetic anisotropy: Helical and circumferential

2001

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This paper concerns the theoretical and experimental investigation of the magneto-impedance (MI) effect in amorphous wires in terms of the surface impedance tensor ςˆ. Physical concepts of MI and problems of significant practical importance are discussed using the results obtained. The theoretical analysis is based on employing the asymptotic-series expansion method of solving the Maxwell equations for a ferromagnetic wire with an ac permeability tensor of a general form associated with magnetisation rotation. The magnetic structure-dependent impedance tensor ςˆ is calculated for any frequency and external magnetic field, and is not restricted to the case when only strong skin-effect is present. This approach allows us to develop a rigorous quantitative analysis of MI characteristics in wires, depending on the type of magnetic anisotropy, the magnitude of dc bias current, and an excitation method. The theoretical model has been tested by comparing the obtained results with experiment. For the sake of an adequate comparison, the full tensor ςî s measured in CoFeSiB and CoSiB amorphous wires having a circumferential and helical anisotropy, respectively, by determining the 21 S parameter. In cases, when the rotational dynamics is responsible for the impedance behaviour, there is a reasonable agreement between the experimental and theoretical results. Such effects as the ac biased asymmetrical MI in wires with a circumferential anisotropy, the transformation in MI behaviour caused by a dc current (from that having a symmetric hysteresis to an asymmetric anhysteretic one) in wires with a helical anisotropy are discussed.

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“…The coil gives an additional source of e.m.f which may cause the amplitude of the ac current to change during the experiment as well. 22,23…”

Section: B Circumferential Anisotropymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Field-dependent surface impedance tensor in amorphous wires with two types of magnetic anisotropy: Helical and circumferential

2001

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“…S INCE a project for new sensitive and quick response micro magnetic sensors utilizing the magneto-impedance (MI) effect in amorphous wires was proposed in 1993 (RQ-8 conference) [1], a number of researches on the MI effect and developments on the MI sensors have been spread in world wide [2]. The CMOS IC MI sensor circuitry is especially important to realize the sensitive, quick response and low power consumption MI micro sensor suitable for ASIC technology [3].…”

Section: Introductionmentioning

confidence: 99%

Improved pulse carrier MI effect by flash anneal of amorphous wires and FM wireless CMOS IC torque sensor

Cai

Mohri

Honkura³

et al. 2001

IEEE Trans. Magn.

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A figure of merit (FOM) for the magneto-impedance (MI) effect is defined by the product of the MI ratio and the cut-off frequency for ac field detection as ( Hex 0 ) cuto . The FOM for almost zero-magnetostrictive amorphous wire of 30 m diameter was about improved 2.5 times by twisting and flash annealing using a pulse current of 80 mA, 1 second. A sensitive, quick response, and low power consumption wireless FM type MI sensor is constituted using the high FOM amorphous wire head combined with all CMOS IC sensor circuit. The wireless MI sensor is successfully applied to a torque sensor fixed on an automobile power steering steel.

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