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Theses

Rectification et supraconductivité de proximité dans des anneaux mésoscopiques

Abstract : This thesis deals with the electronic transport at the mesoscopic scale. That is to say the samples are smaller than Lphi the phase coherence length which corresponds to the length up to which the electrons keep their phase memory and thus can interfere. Lphi increases when temperature decreases (typically, Lphi > 1micron for T < 100mK). This phase coherence yields quantum corrections to the linear conductance G1 (defined by I=G1V+G2V²) which have been studied since the beginning of the 80's. We showed that there is an antisymmetric part in magnetic field of the second order non linear conductance G2 which does not exist in the linear conductance G1 for symmetry reasons (Onsager rules). This term gives informations on the electron-electron interactions. The systems we studied are rings realised in bidimensionnal electron gas. In the second part of my thesis, we placed a normal conductor (i.e. non superconducting) fully coherent between 2 superconductors. In such conditions a supercurrent can flow through the junction. We focused on the phase-current relation Isu(F) in connected superconductor rings which are interrupted by a diffusive metal twice. We observed oscillations in the switching current (Superconductor/Normal) the period of which corresponds to h/(2e) in the area of the ring. The envelop of those oscillations decreases in a gaussian way for high magnetic field and in some cases, it surprisingly increases for low magnetic field.
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https://tel.archives-ouvertes.fr/tel-00156703
Contributor : Lionel Angers <>
Submitted on : Friday, June 22, 2007 - 11:57:27 AM
Last modification on : Wednesday, September 16, 2020 - 4:32:01 PM
Long-term archiving on: : Thursday, April 8, 2010 - 9:10:02 PM

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  • HAL Id : tel-00156703, version 1

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Lionel Angers. Rectification et supraconductivité de proximité dans des anneaux mésoscopiques. Physique [physics]. Université Paris Sud - Paris XI, 2007. Français. ⟨tel-00156703⟩

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