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Défauts topologiques en présence de désordre, et application aux réseaux de vortex dans les supraconducteurs

Abstract : The first introductive part is a review of the usual description of phase transitions induced by topological defects in two dimensions. In particular, the Coulomb gas description is introduced in the context of the Kosterlitz-Thouless transition and the two dimensional continuous melting scenario. The second part concerns the interplay between topological defects and disorder, either coming from structural impurities, or from a substrate. The first study focus on flux lines in superconductors, lying in parallel planes, with substrate disorder. Renormalization techniques and a replica variational theory are used to find a new transition between a quasi-ordered three-dimensional phase (Bragg glass) and an amorphous phase in which dislocation loops proliferate. The effect of this disorder on two dimensional dislocations is then studied using the renormalization group. In this case dislocations are generated by disorder at low temperatures, and the melting transition is replaced by a sharp cross-over whose experimental consequences are discussed. Finally the freezing of defects by disorder at low temperature is studied and requires the developpement of a new functional renormalization technique in two dimensions. This new method allows to study the scaling behaviour of the density of sites favorable to the appearence of defects, and a new type of transition in found at zero temperature due to this freezing.
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https://tel.archives-ouvertes.fr/tel-00010790
Contributor : David Carpentier <>
Submitted on : Wednesday, October 26, 2005 - 9:19:14 PM
Last modification on : Tuesday, December 22, 2020 - 6:40:02 PM
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  • HAL Id : tel-00010790, version 1

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David Carpentier. Défauts topologiques en présence de désordre, et application aux réseaux de vortex dans les supraconducteurs. Analyse de données, Statistiques et Probabilités [physics.data-an]. Université Pierre et Marie Curie - Paris VI, 1999. Français. ⟨tel-00010790⟩

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