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États métastables dans les systèmes désordonnés : des verres de spins aux

Abstract : Glassy materials are characterised by the existence of a large number of metastable states. Amongst these systems spin glasses are the most studied and understood. However dense granular media have recently been shown to be glassy systems, and the role of metastable states here is not yet well understood. In this thesis results and analogies with spin glasses are exploited to study the stationary regime of vibrated granular media.
In the first part of the thesis, the principal properties of the dynamics of mean-field spin glasses are reviewed. The concept of metastable states is discussed along with their role in ergodicity breaking in the glassy phase. Finally several techniques, both analytic and numeric, to calculate the entropy of metastable states are presented in detail.
The second part of the thesis treats metastable states in granular systems. A tapping dynamics is is introduced leading to a, partially analytically tractable, model which serves as a paradigm for vibrated granular media. The scenario proposed by Edwards, where in the stationary state all metastable states are visited with the same probability, is tested on several models. The study of certain one-dimensional models permits one to understand the validity of this approach at high densities, while the study of models on random graphs demonstrates that the Edwards measure allows a description of non-trivial phenomena such as phase transitions. Finally, various tests to verify this approach on experimental systems are proposed.
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Contributor : Alexandre Lefevre <>
Submitted on : Monday, September 8, 2003 - 4:18:29 PM
Last modification on : Saturday, March 28, 2020 - 2:11:20 AM
Long-term archiving on: : Friday, April 2, 2010 - 6:51:48 PM

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  • HAL Id : tel-00003321, version 1

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Alexandre Lefevre. États métastables dans les systèmes désordonnés : des verres de spins aux. Analyse de données, Statistiques et Probabilités [physics.data-an]. Université Paul Sabatier - Toulouse III, 2003. Français. ⟨tel-00003321⟩

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