Dipolar-stabilized first and second-order antiskyrmions in ferrimagnetic multilayers

TL;DR

This paper demonstrates the stabilization of first and second-order antiskyrmions in ferrimagnetic multilayers through dipolar interactions, expanding the understanding of topological spin structures beyond D2d symmetry materials.

Contribution

It introduces a new method to stabilize antiskyrmions in multilayers with modified magnetic properties, using dipole-dipole interactions rather than symmetry constraints.

Findings

Coexistence of antiskyrmions, skyrmions, and bubbles observed.

Antiskyrmions stabilized by dipolar interactions in Fe/Gd multilayers.

Reduction of saturation magnetization and anisotropy enables diverse spin structures.

Abstract

Skyrmions and antiskyrmions are topologically protected spin structures with opposite topological charge. Particularly in coexisting phases, these two types of magnetic quasi-particles may show fascinating physics and potential for spintronic devices. While skyrmions are observed in a wide range of materials, until now antiskyrmions were exclusive to materials with D2d symmetry. In this work, we show first and second-order antiskyrmions stabilized by magnetic dipole-dipole interaction in Fe/Gd-based multilayers. We modify the magnetic properties of the multilayers by Ir insertion layers. Using Lorentz transmission electron microscopy imaging, we observe coexisting antiskyrmions, Bloch skyrmions, and type-2 bubbles and determine the range of material properties and magnetic fields where the different spin objects form and dissipate. We perform micromagnetic simulations to obtain more insight into the studied system and conclude that the reduction of saturation magnetization and uniaxial anisotropy leads to the existence of this zoo of different spin objects and that they are primarily stabilized by dipolar interaction.