Temperature dependence of fluctuation time scales in spin glasses

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Using a series of fast cooling protocols we have probed aging effects in the spin glass state as a function of temperature. Analyzing the logarithmic decay found at very long time scales within a simple phenomenological barrier model, leads to the extraction of the fluctuation time scale of the system at a particular temperature. This is the smallest dynamical time-scale, defining a lower-cut off in a hierarchical description of the dynamics.  We find that this fluctuation time scale, which is approximately equal to atomic spin fluctuation time scales near the transition temperature, follows a generalized Arrhenius law. We discuss the hypothesis that, upon cooling to a measuring temperature within the spin glass state, there is a range of dynamically in-equivalent configurations in which the system can be trapped, and check within a numerical barrier model simulation, that this  leads to sub-aging behavior in scaling aged TRM decay curves, as recently discussed theoretically~\cite{Sibani09}.
JournalPhysical Review B
Pages (from-to)014424
StatePublished - 1 Jan 2010