One of the striking properties of a glassy system is that many material properties depend on its age, i.e., the time since the system entered its glassy phase. In this this talk we shall review some recent progress (work in collaboration with H. E. Castillo, P. Charbonneau, J. L. Iguain, M. P. Kennett, D. R. Reichman and M. Sellitto) in understanding local aging, through the study of local observable quantities, which reveal that there are spatial heterogeneities and fluctuations in the aging process of macroscopic systems. We show that a number of universal properties are shared by many non-equilibrium systems, both with and without quenched disorder, such as the 3D Edwards-Anderson model and some kinetically constrained non-interacting 2D and 3D spin models, for example.
Similar scaling relations are found for mesoscopic sample-to-sample fluctuations of global quantities in small size systems. We discuss how the emergence of a symmetry in aging systems, time-reparametrization invariance, could be responsible for the observed universal behavior of the local and mesoscopic non-equilibrium fluctuations.
The aim of this report is to review a theoretical approach that has
been proposed recently to describe dynamic fluctuations in glassy
systems (work in collaboration with H.E. Castillo, C. Chamon, J. L. Iguain, M. Kennett and M. Sellitto). Firstly, I summarize some of the main features of the averaged and global non-equilibrium relaxation of glassy systems, weakly sheared viscous liquids and weakly tapped granular matter, and how these results have been successfully reproduced with a mean-field-like analytic approach. Secondly, I explain the outcome of more refined experimental and numerical measurements that point at examining the dynamics at a
mesoscopic scale, and the role of noise measurements in this respect. Finally, I discuss how our theoretical approach can be confronted to new experimental and numerical tests.
Conference Committee Involvement (2)
Fluctuations and Noise in Materials
26 May 2004 | Maspalomas, Gran Canaria Island, Spain