Elliptical skyrmions: theory and nucleation by a magnetic tip in an antiskyrmion-hosting material

TL;DR

This paper theoretically and numerically investigates elliptical skyrmions in materials with Dzyaloshinskii-Moriya interaction (DMI), demonstrating their nucleation via magnetic tips and analyzing their properties using analytical and computational methods.

Contribution

It introduces the concept of elliptical skyrmions supported by DMI in antiskyrmion-hosting materials and details their analytical properties and nucleation mechanisms.

Findings

Elliptical skyrmions can be nucleated from stripe domains using a magnetic tip.

DMI can support elliptical skyrmions and antiskyrmions with anisotropic shapes.

Analytical models describe the properties of elliptical skyrmions in these materials.

Abstract

Motivated by experimental findings in [ 1 ] and [ 2 ], we find an elliptical skyrmion can be nucleated in a material with a Dzyaloshinskii-Moriya interaction (DMI) that supports antiskyrmions. The DMI favors the elongation of the skyrmion along a given direction so that it is characterized by two size parameters. We derive analytical properties of the elliptical skyrmion using the Belavin-Polyakov (BP) pure exchange model. We show that the DMI which typically favors isotropic skyrmions or antiskyrmions, respectively, can also support elliptical antiskyrmions or skyrmions, respectively. Using the real material parameters extracted from [1] and including all relevant interactions, numerical computations indicate that the elliptical skyrmion can be nucleated from the stripe or labyrinth domain state by a magnetic force microscope tip in a thin film with a DMI favoring antiskyrmions that consists of at least a few atomic layers.