Excess wings and asymmetric relaxation spectra in a facilitated trap model

Abstract

In a recent computer study, we have shown that the combination of spatially heterogeneous dynamics and kinetic facilitation provides a microscopic explanation for the emergence of excess wings in deeply supercooled liquids. Motivated by these findings, we construct a minimal empirical model to describe this physics and introduce dynamic facilitation in the trap model, which was initially developed to capture the thermally-activated dynamics of glassy systems. We fully characterise the relaxation dynamics of this facilitated trap model varying the functional form of energy distributions and the strength of dynamic facilitation, combining numerical results and analytic arguments. Dynamic facilitation generically accelerates the relaxation of the deepest traps, thus making relaxation spectra strongly asymmetric, with an apparent "excess" signal at high frequencies. For well-chosen values of the parameters, the obtained spectra mimic experimental results for organic liquids displaying an excess wing. Overall, our results identify the minimal physical ingredients needed to describe excess processes in relaxation spectra of supercooled liquids.

11 pages, 9 figures

References in corpus (6)

• Theoretical perspective on the glass transition and amorphous materials
• Dynamic heterogeneity in amorphous materials
• The building blocks of dynamical heterogeneities in dense granular media
• Logarithmic Relaxation in Glass-Forming Systems
• Elastoplasticity Mediates Dynamical Heterogeneity Below the Mode-Coupling Temperature
• A simple spin model for three steps relaxation and secondary proccesses in glass formers

Cited by in corpus (15)

• Thirty milliseconds in the life of a supercooled liquid
• Microscopic origin of excess wings in relaxation spectra of supercooled liquids
• Elasticity, Facilitation and Dynamic Heterogeneity in Glass-Forming liquids
• Solid-that-flows picture of glass-forming liquids
• Relevance of Shear Transformations in the Relaxation of Supercooled Liquids
• Roadmap on machine learning glassy dynamics
• Unified percolation scenario for the $\alpha$ and $\beta$ processes in simple glass formers
• Scaling Description of Dynamical Heterogeneity and Avalanches of Relaxation in Glass-Forming Liquids
• Delayed elastic contributions to the viscoelastic response of foams
• Building a "trap model" of glassy dynamics from a local structural predictor of rearrangements
• Collective dynamics in a glass-former with Mari-Kurchan interactions
• Bringing together two paradigms of non-equilibrium: Fragile versus robust aging in driven glassy systems
• Impulsive stimulated scatttering signal in supercooled liquids with Debye or Havriliak-Negami relaxation of the specific heat capacity and thermal expansion coefficient
• Molecular motion at the experimental glass transition
• Localization properties of the sparse Barrat-Mézard trap model