Mayer Peter, Léonard Sébastien, Berthier Ludovic, Garrahan Juan P, Sollich Peter
Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
Phys Rev Lett. 2006 Jan 27;96(3):030602. doi: 10.1103/PhysRevLett.96.030602. Epub 2006 Jan 25.
In glassy materials, aging proceeds at large times via thermal activation. We show that this can lead to negative dynamical response functions and novel and well-defined violations of the fluctuation-dissipation theorem, in particular, negative fluctuation-dissipation ratios. Our analysis is based on detailed theoretical and numerical results for the activated aging regime of simple kinetically constrained models. The results are relevant to a variety of physical situations, such as aging in glass formers, thermally activated domain growth, and granular compaction.
