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Thème : Structure, vibration, relaxations dans les systèmes désordonnés
Présentation
In the last years important progress has been made on long-standing fundamental questions such as those related to sound properties in glasses and their relation with the universal low-temperature anomalies. A comprehensive picture of the nontrivial frequency dependence of sound attenuation in oxide glasses can now be proposed. It is controlled by three processes which in increasing order of the frequency at which they dominate are : the thermal relaxation of defects, relaxation via anharmonic interactions with the thermal bath, and a remarkably rapid increase (α Ω4) towards a Ioffe-Regel crossover at THz frequencies which we have evidenced in two oxide glasses. The latter mechanism relates to the boson peak and the low temperature plateau generally observed in the thermal conductivity. The close relation between the Ioffe-Regel crossover and the boson peak implies a resonance of these rather local low-lying optic modes with acoustic modes near the Ioffe-Regel limit.
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Dernières publications
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Intermediate-range order governs dynamics in dense colloidal liquids 
Auteur(s): Singh Navneet, Zhang Z., Sood A.k., Kob W. (Article) Publié: Proceedings Of The National Academy Of Sciences Of The United States Of America, vol. 120 p.e2300923120 (2023) |
, Ganapathy Rajesh|
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Topology of vibrational modes predicts plastic events in glasses
Auteur(s): Wu Zhenwei, Chen Yixiao, Wang Wei-hua, Kob W. (Article) Publié: Nature Communications, vol. 14 p.2955 (2023) |
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On the absence of structure factors in concentrated colloidal suspensions and nanocomposites Auteur(s): Genix A.-C., Oberdisse J.
(Article) Publié:
European Physical Journal E, vol. 46 p.46 (2023)
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Innovative experimental setups
Brillouin light scattering (BLS)
We constructed a unique High Resolution Brillouin Spectrometer with the highest precision on acoustic phonon frequencies and linewidth worldwide. It consists (...)
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