Abstract
In the presence of impurities, ferromagnetic and ferroelectric domain walls slide only above a finite external field. Close to this depinning threshold, they proceed by large and abrupt jumps called avalanches, while, at much smaller fields, these interfaces creep by thermal activation. In this Letter, we develop a novel numerical technique that captures the ultraslow creep regime over huge time scales. We point out the existence of activated events that involve collective reorganizations similar to avalanches, but, at variance with them, display correlated spatiotemporal patterns that resemble the complex sequence of aftershocks observed after a large earthquake. Remarkably, we show that events assemble in independent clusters that display at large scales the same statistics as critical depinning avalanches. We foresee these correlated dynamics being experimentally accessible by magnetooptical imaging of ferromagnetic films.
Highlights
Our newly developed algorithm allows us to go deep in the creep regime of an elastic interface moving in a disordered environment
The most striking property emerging from our study of creep events is their occurrence in correlated spatio-temporal patterns, in sharp contrast with depinning avalanches nucleating randomly along the line
Despite the novel properties displayed by such dynamics, we find that the creep law is verified
Summary
In order to make this qualitative comparison more quantitative we analyze here the degree of temporal correlation among creep events by computing the mean squared displacement (MSD), ∆X2(t) , of the (epicenter) location of events separated by t metastable states. In absence of correlations we expect ∆X2(t) = C wit
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