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

Motivated by experimental findings in Jena et al. [1] and Peng et al. [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 Jena et al. [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. •Elliptical skyrmions can be created in a systematic way with an MFM in a material with the DMI that supports antiskyrmions.•Their basic properties can be calculated explicitly in the context of the pure exchange BP 2D model.•The elliptical skyrmion can be nucleated from the stripe domain state or the labyrinth domain state.•The size of the nucleated elliptical skyrmion can be controlled by adjusting the applied field and the tip field strength.•The elliptical skyrmion can have two different chiralities, which are dictated by the initial state it is written from.