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Imagerie magnétique par micro-SQUID à basse température

Abstract : We have conceived and built a microscope associating magnetic imaging at micrometer scale with near field topographic imaging for applications in superconductivity and magnetism. The integration of the micro-SQUID microscope in a dilution refrigerator offers an unexplored field in magnetic imaging. The magnetic field is detected by a micro-SQUID consisting of a 1 micrometer diameter loop interrupted by two Josephson junctions, the micro-SQUID is patterned by electron beam lithography. Topographic imaging is achieved using force microscopy. A quartz tuning fork used as mechanical resonator detects the surface forces. The tip of the silicon chip carrying the micro-SQUID is maintained at a distance of a few nanometers of the sample's surface, giving rise to the topographic image. During imaging the microscope has a magnetic flux sensitivity of 10-3F0/ Hz 1/2 and magnetic spatial resolution better than 2 micrometers. The microscope has allowed us to observe vortex dynamics in a aluminum antidot lattice. We have showed the influence of the antidot size on the pinning of the vortices, the thermal depinning of the vortices at temperatures close to Tc, surface superconductivity and the time relaxation of the quenched vortex distribution.
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https://tel.archives-ouvertes.fr/tel-00004193
Contributor : Nathalie Le Moulec <>
Submitted on : Wednesday, January 21, 2004 - 1:19:24 PM
Last modification on : Friday, December 18, 2020 - 1:34:04 PM
Long-term archiving on: : Wednesday, September 12, 2012 - 12:30:18 PM

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  • HAL Id : tel-00004193, version 1

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UJF | CNRS | UGA

Citation

Cécile Veauvy. Imagerie magnétique par micro-SQUID à basse température. Supraconductivité [cond-mat.supr-con]. Université Joseph-Fourier - Grenoble I, 2002. Français. ⟨tel-00004193⟩

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