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(307) Production(s) de BERTHIER L.


Overlap fluctuations in glassforming liquids
Auteur(s): Berthier L.
(Article) Publié:
Physical Review E: Statistical, Nonlinear, And Soft Matter Physics, vol. 88 p.022313 (2013)
Texte intégral en Openaccess :
Ref HAL: hal00858237_v1
Ref Arxiv: 1306.0425
DOI: 10.1103/PhysRevE.88.022313
WoS: 000323488700001
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
48 Citations
Résumé: We analyse numerically thermal fluctuations of the static overlap between equilibrium configurations in a glassforming liquid approaching the glass transition. We find that the emergence of slow dynamics near the onset temperature correlates with the development of nonGaussian probability distributions of overlap fluctuations, measured using both annealed and quenched definitions. Below a critical temperature, a thermodynamic field conjugate to the overlap induces a firstorder phase transition, whose existence we numerically demonstrate in the annealed case. These results establish that the approach to the glass transition is accompanied by profound changes in the nature of thermodynamic fluctuations, deconstructing the view that glassy dynamics occurs with little structural evolution.



Disentangling glass and jamming physics in the rheology of soft materials
Auteur(s): Ikeda A., Berthier L., Sollich Peter
(Article) Publié:
Soft Matter, vol. 9 p.7669 (2013)
Texte intégral en Openaccess :
Ref HAL: hal00848793_v1
Ref Arxiv: 1302.4271
DOI: 10.1039/C3SM50503K
WoS: 000322230300001
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
84 Citations
Résumé: The shear rheology of soft particles systems becomes complex at large density because crowding effects may induce a glass transition for Brownian particles, or a jamming transition for nonBrownian systems. Here we successfully explore the hypothesis that the shear stress contributions from glass and jamming physics are 'additive'. We show that the experimental flow curves measured in a large variety of soft materials (colloidal hard spheres, microgel suspensions, emulsions, aqueous foams) as well as numerical flow curves obtained for soft repulsive particles in both thermal and athermal limits are well described by a simple model assuming that glass and jamming rheologies contribute linearly to the shear stress, provided that the relevant scales for time and stress are correctly identified in both sectors. Our analysis confirms that the dynamics of colloidal hard spheres is uniquely controlled by glass physics while aqueous foams are only sensitive to jamming effects. We show that for micronsized emulsions both contributions are needed to successfully account for the flow curves, which reveal distinct signatures of both phenomena. Finally, for two systems of soft microgel particles we show that the flow curves are representative of the glass transition of colloidal systems, and deduce that microgel particles are not well suited to studying the jamming transition experimentally.
Commentaires: 16 pages, 10 figures



Probing a Liquid to Glass Transition in Equilibrium
Auteur(s): Kob W., Berthier L.
(Article) Publié:
Physical Review Letters, vol. 110 p.245702 (2013)
PMID 25165938
DOI: 10.1103/PhysRevLett.110.245702
WoS: 000320282600010
86 Citations
Résumé: We use computer simulations to investigate the static properties of a simple glassforming fluid in which the positions of a finite fraction of the particles have been frozen. By probing the equilibrium statistics of the overlap between independent configurations of the liquid, we find strong evidence that this random pinning induces a glass transition. At low temperatures, our numerical findings are consistent with the existence of a random firstorder phase transition rounded by finite size effects.



Nonequilibrium glass transitions in driven and active matter
Auteur(s): Berthier L., Kurchan Jorge
(Article) Publié:
Nature Physics, vol. 9 p.310 (2013)
Texte intégral en Openaccess :
Ref HAL: hal00823177_v1
Ref Arxiv: 1302.4868
DOI: 10.1038/nphys2592
WoS: 000318550200023
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
146 Citations
Résumé: The glass transition, extensively studied in dense fluids, polymers, or colloids, corresponds to a dramatic evolution of equilibrium transport coefficients upon a modest change of control parameter, like temperature or pressure. A similar phenomenology is found in many systems evolving far from equilibrium, such as driven granular media, active and living matter. While many theories compete to describe the glass transition at thermal equilibrium, very little is understood far from equilibrium. Here, we solve the dynamics of a specific, yet representative, class of glass models in the presence of nonthermal driving forces and energy dissipation, and show that a dynamic arrest can take place in these nonequilibrium conditions. While the location of the transition depends on the specifics of the driving mechanisms, important features of the glassy dynamics are insensitive to details, suggesting that an 'effective' thermal dynamics generically emerges at long time scales in nonequilibrium systems close to dynamic arrest.
Commentaires: 7 pages, 2 figs Journal: Nature Phys. 9, 310 (2013)



Equilibrium study of a liquidglass transition
Auteur(s): Berthier L.
Conférence invité: APS March Meeting (Baltimore, US, 20130319)



Dynamic criticality at the jamming transition
Auteur(s): Ikeda A., Berthier L., Biroli Giulio
(Article) Publié:
The Journal Of Chemical Physics, vol. 138 p.12A507 (2013)
Texte intégral en Openaccess :
Ref HAL: hal00770499_v1
Ref Arxiv: 1209.2814
DOI: 10.1063/1.4769251
WoS: 000316969500009
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
64 Citations
Résumé: We characterize vibrational motion occurring at low temperatures in dense suspensions of soft repulsive spheres over a broad range of volume fractions encompassing the jamming transition at (T = 0, phi = phi_J). We find that characteristic time and length scales of thermal vibrations obey critical scaling in the vicinity of the jamming transition. We show in particular that the amplitude and the time scale of dynamic fluctuations diverge symmetrically on both sides of the transition, and directly reveal a diverging correlation length. The critical region near phi_J is divided in three different regimes separated by a characteristic temperature scale T*(phi) that vanishes quadratically with the distance to phi_J. While two of them, (T < T*(phi), phi > phi_J) and (T < T*(phi), phi < phi_J), are described by harmonic theories developed in the zero temperature limit, the third one for T > T*(phi) is inherently anharmonic and displays new critical properties. We find that the quadratic scaling of T*(phi) is due to nonperturbative anharmonic contributions, its amplitude being orders of magnitude smaller than the perturbative prediction based on the expansion to quartic order in the interactions. Our results show that thermal vibrations in colloidal assemblies directly reveal the critical nature of the jamming transition. The critical region, however, is very narrow and has not yet been attained experimentally, even in recent specificallydedicated experiments.
Commentaires: 18 pages; submitted to J. Chem. Phys. for "Special Topic Issue on the Glass Transition"



Statistical physics in the absence of thermal fluctuations
Auteur(s): Berthier L.
Conférence invité: Journees de la matiere condensee (, FR, 20120827)
