Numerical study of the depinning transition of a ferromagnetic magnetic domain wall in films

TL;DR

This study uses numerical simulations to analyze the depinning transition of magnetic domain walls in 2D films, revealing fractal structures, critical scaling, and universality class changes influenced by dipole interactions.

Contribution

It provides the first principle numerical analysis of domain wall depinning in 2D magnetic films, highlighting the impact of dipole interactions on universality classes and critical dynamics.

Findings

Observed fractal structure of domain walls near depinning

Determined universal scaling functions and exponents

Identified transition between two universality classes based on dipole strength

Abstract

We report first principle numerical study of domain wall (DW) depinning in two-dimensional magnetic film, which is modeled by 2D random-field Ising system with the dipole-dipole interaction. We observe nonconventional activation-type motion of DW and reveal its fractal structure of DW near the depinning transition. We determine scaling functions describing critical dynamics near the transition and obtain universal exponents establishing connection between thermal softening of pinning potential and critical dynamics. We observe that tuning the strength of the dipole-dipole interaction switches DW dynamics between two different universality classes corresponding to two distinct dynamic regimes, motion in the random potential and that in the random force.