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Poster De Conférence Année : 2014

Impact of physico-chemical treatments on the low frequency noise of GMI-based magnetometers

Résumé

GMI-based magnetometers offer a competitive alternative to well-established fluxgate magnetometers for relatively low-cost and highly-sensitive magnetometers [1]. While state-of-the-art GMI magnetometers can operate at much higher frequency than fluxgates and exhibit sub-pT/Hz1/2 equivalent magnetic noise, somewhere between 100 Hz and 1 kHz and above, they are, however, plagued by 1/f-noise, degrading their performance at low frequencies. We have recently shown that part of this noise was intrinsic to the GMI sensing elements [2]. Since 1/f noise can be associated with time-dependent fluctuators, such as magnetic fluctuations [3] or electronic noise at an electrical junction, we have speculated that it may originate either from poor electrical contacts or from closure magnetic domains at the GMI microwires extremities. We have thus conducted a study of the effect of various physico-chemical treatments on the GMI performance of CoFeSiBNb GMI wires, whose objective is the establishment of a systematic procedure for wire preparation, yielding wires with reproducible and improved GMI performance. A series of nominally identical microwire segments, with no apparent defects based on optical microscopic observations, were current-annealed under tensile stress. The wires were then divided into different groups, each submitted to a distinct combination of treatments, such as acid etching or laser melting to smooth out the wire extremities, or Cu electroplating to improve the electrical contacts. Characterization of the GMI sensitivity at 10 MHz and of the magnetic noise spectra over a broad frequency range is being carried out on all samples. The effect of each treatment is assessed by comparison of each wire group with the control group, which was not submitted to any treatments, and with complementary characterization by VSM magnetometry and by FMR spectroscopy. The results are compared with predictions for the behavior of uniform cylindrical wires and the noise model developed in Reference [3]. ----------------------------------------------------------- References [1] B. Dufay, S. Saez, C. Dolabdjian, A. Yelon and D. Ménard, Development of a High Sensitivity Giant Magneto-Impedance Magnetometer: Comparison With a Commercial Flux-Gate, IEEE Transactions on magnetics, vol. 49, no. 1 (2013), pp 85-88. [2] B. Dufay, S. Saez, C. Dolabdjian, A. Yelon and D. Ménard, Characterization of an Optimized OFF-Diagonal GMI-Based Magnetometer, IEEE Sensors Journal, vol. 13, no. 1 (2013), pp. 379-388. [3] C. Dolabdjian, B. Dufay, S. Saez, A. Yelon and D. Menard, Is low frequency excess noise of GMI induced by magnetization fluctuations?, International Conference on Materials and Applications for Sensors and Transducers, ICMAST, 2013.

Domaines

Electronique
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Dates et versions

hal-01109731 , version 1 (26-01-2015)

Identifiants

  • HAL Id : hal-01109731 , version 1

Citer

Nicolas Teyssedou, Elodie Portalier, Basile Dufay, Sébastien Saez, Christophe Dolabdjian, et al.. Impact of physico-chemical treatments on the low frequency noise of GMI-based magnetometers. European Magnetic Sensors and Actuators Conference 2014, Jul 2014, Vienne, Austria. ⟨hal-01109731⟩
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