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(21) Production(s) de l'année 2022
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Collective dynamics in a glass-former with Mari-Kurchan interactions 
Auteur(s): Nishikawa Y., Ikeda A., Berthier L.
(Article) Publié:
The Journal Of Chemical Physics, vol. p.244503 (2022)
Texte intégral en Openaccess : 
Ref HAL: hal-03807702_v1
Ref Arxiv: 2204.05130
DOI: 10.1063/5.0096356
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We numerically study the equilibrium relaxation dynamics of a two-dimensional Mari-Kurchan glass model. The tree-like structure of particle interactions forbids both non-trivial structural motifs and the emergence of a complex free-energy landscape leading to a thermodynamic glass transition, while the finite-dimensional nature of the model prevents the existence of a mode-coupling singularity. Nevertheless, the equilibrium relaxation dynamics is shown to be in excellent agreement with simulations performed in conventional glass-formers. Averaged time-correlation functions display a phenomenology typical of supercooled liquids, including the emergence of an excess signal in relaxation spectra at intermediate frequencies. We show that this evolution is accompanied by strong signatures of collective and heterogeneous dynamics which cannot be interpreted in terms of single particle hopping and emerge from dynamic facilitation. Our study demonstrates that an off-lattice interacting particle model with extremely simple structural correlations displays quantitatively realistic glassy dynamics.
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Disordered collective motion in dense assemblies of persistent particles
Auteur(s): Keta Y.-E., Jack Robert L., Berthier L.
(Article) Publié:
Physical Review Letters, vol. p.048002 (2022)
Texte intégral en Openaccess :
Ref HAL: hal-03775859_v1
Ref Arxiv: 2201.04902
DOI: 10.1103/PhysRevLett.129.048002
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We explore the emergence of nonequilibrium collective motion in disordered non-thermal active matter when persistent motion and crowding effects compete, using simulations of a two-dimensional model of size polydisperse self-propelled particles. In stark contrast with monodisperse systems, we find that polydispersity stabilizes a homogeneous active liquid at arbitrary large persistence times, characterized by remarkable velocity correlations and irregular turbulent flows. For all persistence values, the active fluid undergoes a nonequilibrium glass transition at large density. This is accompanied by collective motion, whose nature evolves from near-equilibrium spatially heterogeneous dynamics at small persistence, to a qualitatively different intermittent dynamics when persistence is large. This latter regime involves a complex time evolution of the correlated displacement field
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Rare events and disorder control the brittle yielding of well-annealed amorphous solids
Auteur(s): Ozawa M., Berthier L., Biroli Giulio, Tarjus Gilles
(Article) Publié:
Physical Review Research, vol. 4 p.023227 (2022)
Texte intégral en Openaccess :
Ref HAL: hal-03758384_v1
Ref Arxiv: 2102.05846
DOI: 10.1103/PhysRevResearch.4.023227
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: We use atomistic computer simulations to provide a microscopic description of the brittle failure of amorphous materials, and we assess the role of rare events and quenched disorder. We argue that brittle yielding originates at rare soft regions, similarly to Griffiths effects in disordered systems. We numerically demonstrate how localized plastic events in such soft regions trigger macroscopic failure via the propagation of a shear band. This physical picture, which no longer holds in poorly annealed ductile materials, allows us to discuss the role of finite size effects in brittle yielding and reinforces the similarities between yielding and other disorder-controlled nonequilibrium phase transitions.
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