How a spin-glass remembers. Memory and rejuvenation from intermittency data: an analysis of temperature shifts

Abstract

The memory and rejuvenation aspects of intermittent heat transport are explored theoretically and by numerical simulation for Ising spin glasses with short-ranged interactions. The theoretical part develops a picture of non-equilibrium glassy dynamics recently introduced by the authors. Invoking the concept of marginal stability, this theory links irreversible `intermittent' events, or `quakes' to thermal fluctuations of record magnitude. The pivotal idea is that the largest energy barrier $b(t_w,T)$ surmounted prior to $t_w$ by thermal fluctuations at temperature $T$ determines the rate $r_q\propto 1/t_w$ of the intermittent events occurring near $t_w$. The idea leads to a rate of intermittent events after a negative temperature shift given by $r_q\propto 1/t_w^{eff}$, where the `effective age' $t_w^{eff}\ge t_w$ has an algebraic dependence on $t_w$, whose exponent contains the temperatures before and after the shift. The analytical expression is verified by numerical simulations. Marginal stability suggests that a positive temperature shift $T\to T^{\prime }$ could erase the memory of the barrier $b(t_w,T)$. The simulations show that the barrier $b(t_w,T^{\prime })\ge b(t_w,T)$ controls the intermittent dynamics, whose rate is hence $r_q\propto 1/t_w$. Additional `rejuvenation' effects are also identified in the intermittency data for shifts of both signs.

Revised introduction and discussion. Final version to appear in Journal of Statistical Mechanics: Theory and Experiment

References in corpus (1)

• Comparing extremal and thermal Explorations of Energy Landscapes

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