Spatio-temporal patterns in ultra-slow domain wall creep dynamics

TL;DR

This paper introduces a new numerical method to study ultra-slow domain wall creep, revealing collective, avalanche-like events with complex spatio-temporal patterns similar to earthquake aftershocks, and showing their statistical similarity to critical depinning avalanches.

Contribution

A novel numerical technique captures ultra-slow creep dynamics and uncovers correlated events resembling aftershocks with statistical properties akin to depinning avalanches.

Findings

Identified collective reorganizations with avalanche-like features.

Discovered correlated events with earthquake-like aftershock patterns.

Showed statistical similarity between clusters and critical depinning avalanches.

Abstract

In 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 field, these interfaces creep by thermal activation. In this work we develop a novel numerical technique that captures the ultra-slow 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 spatio-temporal patterns that resemble the complex sequence of aftershocks observed after a large earthquake. Remarkably, we show that events assembly in independent clusters that display at large scales the same statistics as critical depinning avalanches. We foresee this correlated dynamics being experimentally accessible by magneto-optical imaging of ferromagnetic films.