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Supraconductivite et plasmons de surface dans les nanotubes

Abstract : In this work, we present two types of experiments on single nanotubes characterized in parallel by transmission electron microscopy. The first type of experiments was carried out on metal-carbon nanotube -metal junctions. The differential resistances of these junctions were measured at temperatures going from 50 mK to 1K. We showed that it is possible to induce by proximity effect a supercurrent within a rope or a monolayer nanotube, when the contacts are superconducting. When they are normal, an intrinsic superconducting transition in ropes of nanotubes was discovered at temperature down to 500 mK. We analyzed these results taking account the parameters modifying superconductivity in systems with a low number of channels. We thus showed the possibility of observing an ohmic and coherent transport in carbon nanotubes. In the second type of experiments, we looked for the understanding of the dielectric response of multiwalled carbon, boron nitride (BN) and tungsten disulphide (WS2) nanotubes. We made spatially resolved electron energy loss spectroscopy measurements. We first showed the adequacy of a classical description to account for the dielectric properties (1-50 eV) of nanotubes using measurements on carbon and BN nanotubes. The importance of the local anisotropy in the interpretation of the spectra was shown. The same kind of measurements, on WS2 nanotubes with different walls thickness, made it possible to show the existence of electromagnetic surface modes of well defined symmetry resulting from the coupling of the internal and external surfaces modes. A similar interpretation allowed us to analyze the dielectric response of carbon tubes within a classical theory, even when the wall is reduced to a monoatomic sheet.
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https://tel.archives-ouvertes.fr/tel-00004687
Contributor : Mathieu Kociak <>
Submitted on : Monday, February 16, 2004 - 2:43:29 PM
Last modification on : Thursday, November 5, 2020 - 3:54:06 PM
Long-term archiving on: : Wednesday, September 12, 2012 - 1:25:10 PM

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  • HAL Id : tel-00004687, version 1

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Mathieu Kociak. Supraconductivite et plasmons de surface dans les nanotubes. Matière Condensée [cond-mat]. Université Paris Sud - Paris XI, 2001. Français. ⟨tel-00004687⟩

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