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Nouvelles solutions de capteurs à effet de magnétoimpédance géante : principe, modélisation et performances

Abstract : Among the high sensitivity magnetic field measurements principles that are eligible for terrestrial and planetary plasmas wave investigations, Giant MagnetoImpedance (GMI) sensors arouse interest even beyond space applications. Known as the variation of micro-wire, ribbon and sandwich impedance provoked by the magnetic field amplitude, GMI are excited with a high frequency current directly flowing through the ferromagnetic conductor element. It is known that the skin depth is the main responsible phenomenon that involves the giant impedance collapse through the variation of the differential magnetic permeability. Inheriting from the latter principle, new GMI transducers use either one ferromagnetic ribbon with a coil wounded around like planar inductor or either two ribbons gripping the N turns as wounded sandwich. The insulated coil is used both for magnetic excitation and for the measurement, and its inductive behaviour shifts at very low frequency excitation (5kHz- 1MHz), the detection of the static magnetic field or slowly dynamic magnetic field (F<1kHz). Coiled GMI pattern simplify the process of transducer design and improve the magnetic excitation which can be apply in the two ribbon axis direction allowing to access to all component of the anisotropic magnetic permeability tensor corresponding to the relative directions between the static magnetic field and the magnetic anisotropy in a favourable demagnetizing field configuration. The beginning of the present study concerns an experimental investigation of the classical GMI and the coiled GMI using different magnetic material such nanocristallin ribbon annealed under transverse or longitudinal magnetic field, mumetal ribbon and ferrite core. Results have also concerned the main influence of the demagnetizing field occurred in sample with different geometry. Performances criteria are defined by the impedance and the intrinsic sensitivity which replaced the MI ratio. Concluding on the major role of the differential permeability, the work concerns the modeling of the permeability tensor from the Landau-Lisfhitz-Gilbert dynamic magnetization equation combined with monotonous decreasing permeability which has been correlated with the experiment. The model that is proposed consists in a combination between the transverse and longitudinal permeability related to the magnetization rotation mechanism and the longitudinal permeability related to the wall displacement phenomenon. From the electromagnetic model based on the skin effect and the intrinsic parity of the magnetic excitation field appearing in coil, the coiled GMI concept is generalized with the two positions of the coil and both the diagonal component and crossed component of the permeability tensor can be exploited. In order to valid the complete model, the calculated impedance and intrinsic sensitivity are compared to the experimental results in the case of the transverse anisotropy and longitudinal and transverse coil.
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https://tel.archives-ouvertes.fr/tel-00505744
Contributor : Ens Cachan Bibliothèque <>
Submitted on : Monday, July 26, 2010 - 9:18:40 AM
Last modification on : Monday, December 14, 2020 - 9:47:50 AM
Long-term archiving on: : Friday, December 2, 2016 - 12:20:06 AM

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  • HAL Id : tel-00505744, version 1

Citation

Joël Moutoussamy. Nouvelles solutions de capteurs à effet de magnétoimpédance géante : principe, modélisation et performances. Physique [physics]. École normale supérieure de Cachan - ENS Cachan, 2009. Français. ⟨tel-00505744⟩

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