The effect of boundary-induced chirality on magnetic textures in thin films

TL;DR

This paper investigates how boundary-induced Dzyaloshinskii-Moriya interaction (DMI) influences magnetic textures in thin ferromagnetic films, revealing surface twists, domain wall modifications, and increased skyrmion stability due to boundary effects.

Contribution

It demonstrates the impact of boundary-induced DMI on magnetic textures, including surface twists and skyrmion stability, which was not previously characterized.

Findings

Surface twist occurs due to boundary-induced DMI in uniformly magnetized films.

Boundary-induced DMI increases the skyrmion radius and contributes to its stability.

Surface effects significantly alter domain wall width and magnetic configurations.

Abstract

In the quest for miniaturizing magnetic devices, the effects of boundaries and surfaces become increasingly important. Here we show how the recently predicted boundary-induced Dzyaloshinskii-Moriya interaction (DMI) affects the magnetization of ferromagnetic films with a $C_{\infty v}$ symmetry and a perpendicular magnetic anisotropy. For an otherwise uniformly magnetized film, we find a surface twist when the magnetization in the bulk is canted by an in-plane external field. This twist at the surfaces caused by the boundary-induced DMI differs from the common canting caused by internal DMI observed at the edges of a chiral magnet. Further, we find that the surface twist due to the boundary-induced DMI strongly affects the width of the domain wall at the surfaces. We also find that the skyrmion radius increases in the depth of the film, with the average size of the skyrmion increasing with boundary-induced DMI. This increase suggests that the boundary-induced DMI contributes to the stability of the skyrmion.