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Physique Statistique
(56) Production(s) de l'année 2018
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When is the Gardner transition relevant?
Auteur(s): Scalliet C.
(Séminaires)
Duke University (Durham, North Carolina, US), 2018-04-24
Résumé: The idea that glasses can become marginally stable at a Gardner transition has attracted significant interest among the glass community. Yet, the situation is confusing: even at the theoretical level, renormalization group approaches provide contradictory results on whether the transition can exist in three dimensions. The Gardner transition was searched in only two experimental studies and few specific numerical models. These works lead to different conclusions for the existence of the transition, resulting in a poor understanding of the conditions under which a marginally stable phase can be observed. The very relevance of the Gardner transition for experimental glasses is at stake.
We study analytically and numerically the Weeks-Chandler-Andersen model. By changing external parameters, we continuously explore the phase diagram and regimes relevant to granular, colloidal, and molecular glasses. We revisit previous numerical studies and confirm their conclusions. We reconcile previous results and rationalise under which conditions a Gardner phase can be observed. We find that systems in the vicinity of a jamming transition possess a Gardner phase. Our findings confirm the relevance of a Gardner transition for colloidal and granular glasses, and encourage future experimental work in this direction. For molecular glasses, we find that no Gardner phase is present, but our studies reveal instead the presence of localised excitations presumably relevant for mechanical and vibrational properties of glasses.
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A lecture on the glass transition
Auteur(s): Berthier L.
Conférence invité: Liquid Matter 2014 (Lisbonne, PT, 2018-08-21)
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Facets of glass physics
Auteur(s): Berthier L.
Conférence invité: Future of Chemical Physics (Oxford, GB, 2018-08-31)
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Spatio-temporal dynamics of vegetation cover in the «Grand Bagnas» lagoon (France) using remote sensing approach
Auteur(s): Pitard E.
(Séminaires)
Ocean and Estuary Science, San Francisco State University (SFSU) (Tiburon CA, US), 2018-07-27 |
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Spatio-temporal dynamics of vegetation cover in the «Grand Bagnas» lagoon(France) using remote sensing approach
Auteur(s): Pitard E.
(Séminaires)
University of California at Davis (Davis, CA, US), 2018-07-24 |
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Random critical point separates brittle and ductile yielding transitions in amorphous materials
Auteur(s): Ozawa M.
Conférence invité: Yielding versus depinning in disordered systems (Paris, FR, 2018-10-22)
Ref HAL: hal-01939449_v1
Exporter : BibTex | endNote
Résumé: We combine an analytically solvable mean-field elasto-plastic model with molecular dynamics simulations of a generic glass former to demonstrate that, depending on their preparation protocol, amorphous materials can yield in two qualitatively distinct ways. We show that well-annealed systems yield in a discontinuous brittle way, as metallic and molecular glasses do. Yielding corresponds in this case to a first-order nonequilibrium phase transition. As the degree of annealing decreases, the first-order character becomes weaker and the transition terminates in a second-order critical point in the universality class of an Ising model in a random field. For even more poorly annealed systems, yielding becomes a smooth crossover, representative of the ductile rheological behavior generically observed in foams, emulsions, and colloidal glasses. Our results show that the variety of yielding behaviors found in amorphous materials does not necessarily result from the diversity of particle interactions or microscopic dynamics but is instead unified by carefully considering the role of the initial stability of the system.
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A unified picture of yielding in amorphous solids
Auteur(s): Ozawa M.
Conférence invité: Viscous Liquids and the Glass Transition (XV) (Sominestationen, DK, 2018-06-21)
Ref HAL: hal-01939440_v1
Exporter : BibTex | endNote
Résumé: We combine an analytically solvable mean-field elasto-plastic model with molecular dynamics simulations of a generic glass former to demonstrate that, depending on their preparation protocol, amorphous materials can yield in two qualitatively distinct ways. We show that well-annealed systems yield in a discontinuous brittle way, as metallic and molecular glasses do. Yielding corresponds in this case to a first-order nonequilibrium phase transition. As the degree of annealing decreases, the first-order character becomes weaker and the transition terminates in a second-order critical point in the universality class of an Ising model in a random field. For even more poorly annealed systems, yielding becomes a smooth crossover, representative of the ductile rheological behavior generically observed in foams, emulsions, and colloidal glasses. Our results show that the variety of yielding behaviors found in amorphous materials does not necessarily result from the diversity of particle interactions or microscopic dynamics but is instead unified by carefully considering the role of the initial stability of the system.
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