Abstract
Caroline Crauste-Thibierge: „Experimental study of a dynamical correlation length near the glass transition”
Laboratoire Leon Brillouin, Saclay, France
Many liquids do not crystallize when they are cooled down. Their viscosity goes up very fast and they freeze in a disordered solid, called glass. This phenomenon is still poorly understood. The very useful glass transition scenario of dynamical heterogeneities supposes that molecules movements are correlated in clusters growing in size when temperature is lowered, as in a phase transition. This had never been measured in supercooled liquids.
In order to measure these correlations, two methods were proposed by Bouchaud and Biroli [1-2], based one on linear and one on non linear susceptibility measurements. From linear measurements we have extracted a number of correlated molecules growing when the temperature goes to the glass transition temperature [3].
The non linear susceptibility measurement was more difficult to perform since the non linear signal is very small. Then we specially developed an original experimental setup that I will present.
Our measurements show that the number of correlated molecules grows when temperature is lowered. The frequency dependence of non-linear response presents a nice scaling that can be compared to different models. These first of the kind experimental results give an interpretation of glass transition in terms of critical phenomenon [4].
References
- Berthier L, Biroli G, Bouchaud J-P, Cipeletti L, El Masri D, L’Hôte D, Ladieu F and Pierno M 2005 Science 310 1797
- Bouchaud and Biroli PRB 72 064204 (2005)
- Dalle-Ferrier, C. Thibierge, C. Alba-Simionesco, L. Berthier, G. Biroli, J.-P. Bouchaud, F. Ladieu, D. L'Hôte, and G. Tarjus Phys. Rev. E 76, 041510 (2007)
- Crauste-Thibierge, Brun, Ladieu, L'Hôte, Biroli, Bouchaud, Physical Review Letters 104 165703 (2010)