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Transition vitreuse, hétérogénéité dynamique et vieillissement dans les systèmes a dynamique lente
(39) Production(s) de l'année 2019
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How glasses break: A randomcritical point for yielding
Auteur(s): Berthier L.
Conférence invité: Avalanche dynamics and precursors of catastrophic events (Les Houches, FR, 2019-02-04)
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Low-frequency vibrational modes of stable glasses
Auteur(s): Wang Lijin, Ninarello A. S., Guan Pengfei, Berthier L., Szamel G., Flenner Elijah
(Article) Publié:
Nature Communications, vol. 10 p.26 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-01993807_v1
Ref Arxiv: 1804.08765
DOI: 10.1038/s41467-018-07978-1
WoS: 000454756900003
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
41 Citations
Résumé: We numerically study the evolution of the vibrational density of states $D(\omega)$ of zero-temperature glasses when their kinetic stability is varied over an extremely broad range, ranging from poorly annealed glasses obtained by instantaneous quenches from above the onset temperature, to ultrastable glasses obtained by quenching systems thermalised below the experimental glass temperature. The low-frequency part of the density of states splits between extended and quasi-localized modes. Extended modes exhibit a boson peak crossing over to Debye behaviour ($D(\omega) \sim \omega^2$) at low-frequency, with a strong correlation between the two regimes. Quasi-localized modes instead obey $D(\omega) \sim \omega^4$, irrespective of the glass stability. However, the prefactor of this quartic law becomes smaller in more stable glasses, and the corresponding modes become more localized and sparser. Our work is the first numerical observation of quasi-localized modes in a regime relevant to experiments, and it establishes a direct connection between glass stability and soft vibrational motion in amorphous solids.
Commentaires: 8 pages, 6 figures.Nat. Commun. 10, 26 (2019), https://rdcu.be/bfkWJ
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Probing shear-induced rearrangements in Fourier space. I. Dynamic light scattering
Auteur(s): Aime S., Cipelletti L.
(Article) Publié:
Soft Matter, vol. 15 p.200-212 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-01982836_v1
DOI: 10.1039/c8sm01563e
WoS: WOS:000454947400016
Exporter : BibTex | endNote
5 Citations
Résumé: Understanding the microscopic origin of the rheological behavior of soft matter is a long-lastingendeavour. While early efforts concentrated mainly on the relationship between rheology and structure,current research focuses on the role of microscopic dynamics. We present in two companion papers athorough discussion of how Fourier space-based methods may be coupled to rheology to shed light onthe relationship between the microscopic dynamics and the mechanical response of soft systems. In thisfirst companion paper, we report a theoretical, numerical and experimental investigation of dynamiclight scattering coupled to rheology. While in ideal solids and simple viscous fluids the displacement fieldunder a shear deformation is purely affine, additional non-affine displacements arise in many situationsof great interest, for example in elastically heterogeneous materials or due to plastic rearrangements.We show how affine and non-affine displacements can be separately resolved by dynamic lightscattering, and discuss in detail the effect of several non-idealities in typical experiments.
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Probing shear-induced rearrangements in Fourier space. II. Differential dynamic microscopy
Auteur(s): Aime S., Cipelletti L.
(Article) Publié:
Soft Matter, vol. 15 p.213-226 (2019)
Texte intégral en Openaccess :
Ref HAL: hal-01982835_v1
DOI: 10.1039/c8sm01564c
WoS: WOS:000454947400017
Exporter : BibTex | endNote
3 Citations
Résumé: We discuss in two companion papers how Fourier-space measurements may be coupled to rheologicaltests in order to elucidate the relationship between mechanical properties and microscopic dynamics insoft matter. In this second companion paper, we focus on Differential Dynamic Microscopy (DDM)under shear. We highlight the analogies and the differences with dynamic light scattering coupled torheology, providing a theoretical approach and practical guidelines to separate the contributions toDDM arising from the affine and the non-affine part of the microscopic displacement field. We showthat in DDM under shear the coherence of the illuminating source plays a key role, determining theeffective sample thickness that is probed. Our theoretical analysis is validated by experiments on 2Dsamples and 3D gels.
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