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Mesure de l'état fondamental d'une jonction Josephson ferromagnétique

Abstract : We have measured the pi-coupling in Ferromagnet Josephson junctions based on the superconductor Nb and the ferromagnetic alloy PdNi. We have measured the ground state of ferromagnetic Josephson junctions Nb/NbOx/PdNi/Nb (SIFS) as a function of the ferromagnetic layer thickness using a single dc-SQUID (Superconducting QUantum Interfererence Device). The sign change of the Josephson coupling is observed as a shift of half a quantum flux in the SQUID diffraction pattern. We have also studied the Josephson coupling in Nb/PdNi/Nb (SFS) junctions, 100*100 um2 large, with the aim to observe a 0-pi transition as a function of the temperature. The quality of the diffraction pattern on one hand, and the large value of the critical current on the other hand did not allow us to observe this transition. The problems associated with the impossibility to observe this transition has motivated us to develop a new evaporation technic using masks made off membranes of silicium. This system allows us the evaporation of junctions with a size of 25*25 um2 in situ, using masks instead of optical lithography.
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https://tel.archives-ouvertes.fr/tel-00004242
Contributor : Nathalie Le Moulec <>
Submitted on : Wednesday, January 21, 2004 - 1:12:06 PM
Last modification on : Friday, December 18, 2020 - 1:34:03 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:37:06 PM

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  • HAL Id : tel-00004242, version 1

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Wiebke Guichard. Mesure de l'état fondamental d'une jonction Josephson ferromagnétique. Matière Condensée [cond-mat]. Université Joseph-Fourier - Grenoble I, 2003. Français. ⟨tel-00004242⟩

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