14 January, 2010
Dynamical heterogeneities : experimental and simulation results
Abstract
Dynamic heterogeneity now occupies a central place in the field of the glass transition, and the literature dedicated to understanding spatially and temporally heterogeneous relaxation is impressive. Therefore, the scope of these two lectures can only be very limited, and I will only try to convey the generic philosophy and physical aspects underlying these numerous studies, rather than entering the details of specific measurements. I will discuss more particularly the use of multi-point correlation functions that were thoroughly studied by theory, simulations and experiments. I will emphasize in particular the technical difficulties behind these measurements, and the possible ambiguities plaguing their interpretation, trying to answer the following two questions. What have we learnt from these studies? What remains to be done?
The outline of the two lectures should be as follows:
- Dynamic heterogeneity as seen from single particle dynamics, relevant timescales and length scales, modelling using continuous time random walks, and application to decoupling phenomena.
- Dynamic correlations: qualitative descriptions, quantitative measurements using 4-point correlation functions.
- Linear response theory and three-point dynamic susceptibilities: experimental and numerical results.
- Some perspectives chosen among: heterogeneous dynamics in granular and colloidal assemblies near the jamming transition, in interacting colloids near gelation, possible link between static and dynamic correlations.
References and suggested reading
- M. D. Ediger, Annu. Rev. Phys. Chem. 51, 99 (2000)
- P. Chaudhuri, L. Berthier, and W. Kob, Phys. Rev. Lett. 99, 060604 (2007)
- C. Toninelli, M. Wyart, L. Berthier, G. Biroli, and J.-P. Bouchaud, Phys. Rev. E 71, 041505 (2005)
- C. Dalle-Ferrier, C. Thibierge, C. Alba-Simionesco, L. Berthier, G. Biroli, J.-P. Bouchaud, F. Ladieu, D. L'Hote, and G. Tarjus, Phys. Rev. E 76, 041510 (2007).