Motion of discrete interfaces in periodic media

TL;DR

This paper investigates how discrete interfaces move in periodic media, revealing that their motion depends on microstructure details beyond static energy limits, leading to a new homogenized velocity description.

Contribution

It demonstrates that interface motion in periodic media is influenced by microstructure features not captured by static energy limits, introducing a new homogenized velocity.

Findings

Pinning threshold depends on microstructure

Effective motion is governed by a new homogenized velocity

Motion depends on geometrical features beyond $ ext{Gamma}$-limit

Abstract

We study the motion of discrete interfaces driven by ferromagnetic interactions in a two-dimensional periodic environment by coupling the minimizing movements approach by Almgren, Taylor and Wang and a discrete-to-continuous analysis. The case of a homogeneous environment has been recently treated by Braides, Gelli and Novaga, showing that the effective continuous motion is a flat motion related to the crystalline perimeter obtained by $\Gamma$-convergence from the ferromagnetic energies, with an additional discontinuous dependence on the curvature, giving in particular a pinning threshold. In this paper we give an example showing that in general the motion does not depend only on the $\Gamma$-limit, but also on geometrical features that are not detected in the static description. In particular we show how the pinning threshold is influenced by the microstructure and that the effective motion is described by a new homogenized velocity.