Europhys. Lett.
Volume 73, Number 1, January 2006
Page(s) 69 - 75
Section Condensed matter: structural, mechanical and thermal properties
Published online 23 November 2005
Europhys. Lett., 73 (1), pp. 69-75 (2006)
DOI: 10.1209/epl/i2005-10352-3

Mesoscopic fluctuations and intermittency in aging dynamics

P. Sibani

Fysisk Institut, SDU - DK-5230 Odense M, Denmark

received 7 June 2005; accepted in final form 27 October 2005
published online 23 November 2005

Mesoscopic aging systems are characterized by large intermittent noise fluctuations. In a record dynamics scenario (SIBANI P. and DALL J., Europhys. Lett., 64 (2003) 8) these events, quakes, are treated as a Poisson process with average $\alpha
\ln(1 + t/t_w)$, where t is the observation time, tw is the age and $\alpha$ is a parameter. Assuming for simplicity that quakes constitute the only source of de-correlation, we present a model for the probability density function (PDF) of the configuration autocorrelation function. Beside $\alpha$, the model has the average quake size 1/q as a parameter. The model autocorrelation PDF has a Gumbel-like shape, which approaches a Gaussian for large t/tw and becomes sharply peaked in the thermodynamic limit. Its average and variance, which are given analytically, depend on t/tw as a power law and a power law with a logarithmic correction, respectively. Most predictions are in good agreement with data from the literature and with the simulations of the Edwards-Anderson spin-glass carried out as a test.

65.60.+a - Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.
75.10.Nr - Spin-glass and other random models.

© EDP Sciences 2005