In presence of impurities, ferromagnetic and ferroelectric domain walls slide only above a finite external field. Close to this depinning threshold, the wall proceeds by large and abrupt jumps, called avalanches, while, at much smaller field, it creeps by thermal activation.
In our work we developed a novel numerical technique that captures the ultra-slow creep regime over huge time scales, allowing us to access the regime of very low force and temperature.
Thanks to this technique we point out the existence of activated events that involve collective reorganizations similar to avalanches, but, at variance with them, display correlated spatio-temporal patterns that recall the complex sequence of aftershocks observed after a large earthquake.
Remarkably, we show that events assembly in independent clusters owning the same scale-free statistics as critical depinning avalanches.
This correlated dynamics should be experimentally accessible by magneto-optical imaging of ferromagnetic films.