Micromagnetics of thin films in the presence of Dzyaloshinskii-Moriya interaction

TL;DR

This paper analyzes the effects of Dzyaloshinskii-Moriya interaction on thin magnetic films, deriving a simplified model through gamma-convergence and validating it with numerical simulations.

Contribution

It provides a rigorous derivation of the thin-film limit of micromagnetic energy with DMI and compares it with the full 3D model using finite element methods.

Findings

DMI contributes to shape anisotropy in thin films.

The thin-film limit is rigorously derived via gamma-convergence.

Numerical simulations validate the reduced model.

Abstract

In this paper, we study the thin-film limit of the micromagnetic energy functional in the presence of bulk Dzyaloshinskii-Moriya interaction (DMI). Our analysis includes both a stationary $\Gamma$-convergence result for the micromagnetic energy, as well as the identification of the asymptotic behavior of the associated Landau-Lifshitz-Gilbert equation. In particular, we prove that, in the limiting model, part of the DMI term behaves like the projection of the magnetic moment onto the normal to the film, contributing this way to an increase in the shape anisotropy arising from the magnetostatic self-energy. Finally, we discuss a convergent finite element approach for the approximation of the time-dependent case and use it to numerically compare the original three-dimensional model with the two-dimensional thin-film limit.