Influence of the sensor shape on permalloy/Cu/permalloy magnetoimpedance

Rivero, Miguel Ángel; Maícas, M.; López, E.; Aroca, C.; Sánchez, Mónica Llano; Sánchez, P.

doi:10.1016/s0304-8853(02)00926-5

Cited by 30 publications

(13 citation statements)

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“…4 This structure involves a conductive track between two ferromagnetic layers. Fe-based amorphous or nanocrystalline ferromagnetic materials, [5][6][7][8][9][10] particularly NiFe, 4,[11][12][13][14] have been studied leading to magneto-impedance up to 400% at excitation frequencies in a range of several tens to several hundreds of MHz. However, these high frequencies, linked to under-μm thicknesses, make difficult the integration of an associated electronics.…”

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confidence: 99%

Shape Anisotropy in Magneto-Impedance NiFe-Based Microsensors

Cortés

Peng

Woytasik

et al. 2015

J. Electrochem. Soc.

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The magneto-impedance response of narrow multilayered NiFe/Cu/NiFe structures realized by micromolding has been characterized as a function of both the excitation frequency and the magnetic field. It has been found that intrinsic magnetic properties do not depend on the ferromagnetic geometry, but properties linked to the applied magnetic field, i.e. anisotropy field and magneto-impedance value do. The results are consistent with numerical simulations and show that the anisotropy field varies with the ferromagnetic film thickness. The highest magneto-impedance variation and anisotropy field, 170% and 4200 A/m were found for the narrowest and thickest structure. Magneto-impedance effect is based on the impedance variations of a ferromagnetic material due to changes of the skin depth while supplying the material with an AC current and applying an external magnetic field. The skin depth itself varies with the transverse (in case of a film) or circular (in case of a wire) magnetic permeability, thus to the external applied magnetic field:where f is the excitation current frequency going through the material, σ the electrical conductivity and μ t or μ c the magnetic permeability. The impedance depends on the skin effect and the highest variations are obtained for frequencies where the skin depth approximately matches the wire radius or the film half thickness. Values of several hundreds of % have been reported with microwires of amorphous Fe-based alloys, 1,2 thanks to the particular configuration of magnetic domains in rapidly quenched wires. Indeed, the rapid cooling of the material leads to a longitudinal magnetization in the core and a circular magnetization in the shell. The permeability is thus particularly sensitive with the external applied field. Such high magneto-impedance variations together with the use of soft materials lead to high sensitivities to the external magnetic field. Thus, that presents potential applications to small magnetic field measurement or magnetic nanoparticles detection. 3Thin film technology has also been investigated in order to benefit from the ability of collective fabrication process. However, the use of flat configurations and the contact with the substrate can create pinning sites for magnetic domains displacement or can induce stress which hardens the material and lowers the magneto-impedance properties. However large variations have been obtained by using a multilayered structure.4 This structure involves a conductive track between two ferromagnetic layers. Fe-based amorphous or nanocrystalline ferromagnetic materials, 5-10 particularly NiFe, 4,11-14 have been studied leading to magneto-impedance up to 400% at excitation frequencies in a range of several tens to several hundreds of MHz. However, these high frequencies, linked to under-μm thicknesses, make difficult the integration of an associated electronics. In order to decrease the excitation frequency, thick film technology has been investigated. In this way, electrodeposition of NiFe and Cu thin films has been used for ...

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confidence: 99%

Shape Anisotropy in Magneto-Impedance NiFe-Based Microsensors

Cortés

Peng

Woytasik

et al. 2015

J. Electrochem. Soc.

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“…The GMI effect refers to a large change in alternating current (AC) impedance of a soft magnetic conductor when subjected to an external magnetic field [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. It was found that the sandwich films [19][20][21] could have significant GMI effect even at relatively low frequencies (o10 MHz), in particular, the meander-line sandwich films are highly sensitive to the external magnetic field [22,23], and are very suitable for magnetic sensing applications.…”

Section: Introductionmentioning

confidence: 99%

Detection of the magnetite by giant magnetoimpedance sensor

et al. 2015

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“…Structurally, the sandwich F (ferromagnetic)/M (metal)/F (ferromagnetic) has been proved more intensively effective than the single layer film [5]. Furthermore, it was reported that GMI effect could be enhanced in the meander geometrical structure rather than straight line due to the additional inductance from the sample shape [6]. But few reports have been present on the influence of geometrical shape.…”

Section: Introductionmentioning

confidence: 99%

“…Permalloy NiFe film is an excellent ferromagnetic material for its low magnetostrictive coefficient and good soft magnetic properties, which has been used widely for GMI effect [6,7]. Therefore in this paper, by MEMS technique we fabricate the meander sandwich NiFe/Cu/ NiFe film and investigate and compare the GMI effect in both meander and straight-line structures.…”

Section: Introductionmentioning

confidence: 99%