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Article Dans Une Revue Nature Physics Année : 2022

Microscopic origin of excess wings in relaxation spectra of supercooled liquids

Benjamin Guiselin
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Camille Scalliet
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Ludovic Berthier

Résumé

Glass formation is encountered in diverse materials. Experiments have revealed that dynamic relaxation spectra of supercooled liquids generically become asymmetric near the glass transition temperature, Tg, where an extended power law emerges at high frequencies. The microscopic origin of this "wing" remains unknown, and was so far inaccessible to simulations. Here, we develop a novel computational approach and study the equilibrium dynamics of model supercooled liquids near Tg. We demonstrate the emergence of a power law wing in numerical spectra, which originates from relaxation at rare, localised regions over broadly-distributed timescales. We rationalise the asymmetric shape of relaxation spectra by constructing an empirical model associating heterogeneous activated dynamics with dynamic facilitation, which are the two minimal physical ingredients revealed by our simulations. Our work offers a glimpse of the molecular motion responsible for glass formation at relevant experimental conditions.
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Dates et versions

hal-03662093 , version 1 (15-04-2024)

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Benjamin Guiselin, Camille Scalliet, Ludovic Berthier. Microscopic origin of excess wings in relaxation spectra of supercooled liquids. Nature Physics, 2022, 18 (4), pp.468-+. ⟨10.1038/s41567-022-01508-z⟩. ⟨hal-03662093⟩
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