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Supraconductivité de proximité dans les nanostructures métalliques artificielles

Hervé Courtois 1
1 CP
CRTBT - Centre de Recherches sur les Très Basses Températures
Abstract : We studied the proximity superconductivity in a mesoscopic system comprising a normal metal N in contact with superconducting islands S. A method of oblique metal evaporation metal on a suspended submicronic mask was developed under ultra-high vacuum, enabling us to control the quality of the N-S interface from a perfect metal contact to a barrier tunnel. We present a new type of high-frequency broad band filter, minituarized on a copper substrate, effective until very high frequency (20 GHz) and dedicated to the absolute filtering of mesoscopic samples. Measurements of transport until very low temperature (20 mK) show that the behavior of transport in a normal metal in proximity with a superconductor strongly depends on the microscopic parameters which are the length of coherence of the pairs of electrons, the barrier-equivalent length at the interface and the side dimension of the junctions. The Josephson coupling shows a new behavior in temperature, described by the traditional models in a clean mode for the normal coherence length. Observation of phase-slip centers at low temperature exemplifies the gapless character of proximity superconductivity. In a geometry of bidimensionnal network, a new mode of extreme anisotropy is carried out, being characterized by a very pricked oscillation of the temperature of resistive transition according to the magnetic field. In a normal metallic loop, a magnetic flux makes it possible to control the interference between the superconductive currents according to an effect of the type SQUID. The corrections of conductance related to the weak localization in the normal metal in the vicinity of an N-S interface are also discussed. We present finally a decisive experiment in order to test the effect of Coulomb blockade on proximity effect in a N-S tunnel junction.
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Submitted on : Monday, November 27, 2006 - 11:48:53 PM
Last modification on : Friday, December 18, 2020 - 1:34:04 PM
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  • HAL Id : tel-00116792, version 1




Hervé Courtois. Supraconductivité de proximité dans les nanostructures métalliques artificielles. Physique [physics]. Université Joseph-Fourier - Grenoble I, 1994. Français. ⟨tel-00116792⟩



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