Linear response in aging glassy systems, intermittency and the Poisson statistics of record fluctuations
Institut for Fysik og Kemi, SDU, 5230 Odense M, Denmark
Corresponding author: a email@example.com
Revised: 18 May 2007
Published online: 14 September 2007
We study the intermittent behavior of the energy decay and the linear magnetic response of a glassy system during isothermal aging after a deep thermal quench, using the Edward-Anderson spin glass model as a paradigmatic example. The large intermittent changes in the two observables occur in a correlated fashion and through irreversible bursts, `quakes', which punctuate reversible and equilibrium-like fluctuations of zero average. The temporal distribution of the quakes is a Poisson distribution with an average growing logarithmically on time, indicating that the quakes are triggered by record sized fluctuations. As the drift of an aging system is to a good approximation subordinated to the quakes, simple analytical expressions [Sibani et al. Phys Rev B 74, 224407 (2006)] are available for the time and age dependence of the average response and average energy. These expressions are shown to capture the time dependencies of the EA simulation results. Finally, we argue that whenever the changes of the linear response function and of its conjugate autocorrelation function follow from the same intermittent events a fluctuation-dissipation-like relation can arise between the two in off-equilibrium aging.
PACS: 65.60.+a – Thermal properties of amorphous solids and glasses / 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion / 61.43.Fs – Glasses / 75.10.Nr – Spin-glass and other random models
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007