Intermittent collective dynamics of domain walls in the creep regime

TL;DR

This paper investigates the ultra slow, intermittent motion of magnetic domain walls in ferromagnetic thin films, revealing creep avalanches and emphasizing the importance of depinning physics over equilibrium models.

Contribution

It provides experimental evidence of creep avalanches and clarifies the large-scale geometry of domain walls in the creep regime, highlighting depinning as a better descriptive framework.

Findings

Identification of broad size and waiting-time distributions of avalanches

Evidence that domain wall geometry aligns with depinning rather than equilibrium models

Observation of thermally activated, correlated elementary events during domain wall jumps

Abstract

We study the ultra slow domain wall motion in ferromagnetic thin films driven by a weak magnetic field. Using time resolved magneto-optical Kerr effect microscopy, we access to the statistics of the intermittent thermally activated domain wall jumps between deep metastable states. Our observations are consistent with the existence of creep avalanches: roughly independent clusters with broad size and ignition waiting-time distributions, each one composed by a large number of spatio-temporally correlated thermally activated elementary events. Moreover, we evidence that the large scale geometry of domain walls is better described by depinning rather than equilibrium universal exponents.