Sensitivity performance of magnetic field sensor based on magnonic crystals
Résumé
Recent works [1, 2] presented an exploratory investigation of high sensitive magnetic field sensors based on magnonic crystals. They highlighted their strong potential for detecting weak magnetic fields with small-sized sensor operated at room temperature. The working principle relies on the propagation of surface magnetostatic spin-wave through a periodic structure, called magnonic crystals. These materials are made by periodically spatially modulating the magnetic properties along the propagation line of the spin wave. This structure acts as a reflector whenever the spatial periodicity matches the spin wave wavelength, resulting in a band-gap in the transmission spectrum. In [1, 2], the measurement of the complex transmission coefficient (S 21) shows a significant frequency shift of the band-gap absorption peak depending on the applied DC magnetic field. As a consequence, authors propose to use these variations as a magnetic field sensor. We investigate the ability of magnonic crystals to be used as a magnetometer and measured its expected output sensitivity, expressed in unit of V/T, according to the external magnetic field variations. For this, a sine electromagnetic wave at a fixed frequency, f exc = 1 GHz, is applied to the magnonic crystal. The induced spin wave propagates along the main length direction. When the external DC magnetic field varies, the amplitude of the sensed signal at f exc strongly changes, resulting in an AM signal. Based on a classical amplitude demodulation conditioning circuitry, an output sensitivity of 200 V/T is obtained. Considering, presently, that dominating noise sources are those due to the electronic conditioning circuitry, such results allow to predict a sensor equivalent magnetic noise level around 20 pT/√Hz in white noise region.
Domaines
ElectroniqueOrigine | Fichiers produits par l'(les) auteur(s) |
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