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

Michael Heigl,Marek Vaňatka,Manfred Albrecht,Sabri Koraltan,Julian Hintermayr,Aladin Ullrich,Timo Schmidt,Dirk Grundler,Robert Kraft,Christoph Vogler,Michal Urbánek,Anna Semisalova,Michael Farle,Dieter Suess,Claas Abert,Ping Che

doi:10.1038/s41467-021-22600-7

Abstract

Skyrmions and antiskyrmions are topologically protected spin structures with opposite vorticities. 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 magnetic anisotropy leads to the existence of this zoo of different spin objects and that they are primarily stabilized by dipolar interaction.

Highlights

Skyrmions and antiskyrmions are topologically protected spin structures with opposite vorticities
While there have been many predictions of antiskyrmions stabilized by magnetic dipolar interaction[20,21], interface DMI22,23, and noncentrosymmetric D2d symmetry[20,24,25], until now, only the latter could be experimentally realized in Heusler compounds[26,27,28,29]
Antiskyrmions in themselves are of interest for spintronic devices, but especially magnetic phases with a multitude of topologically protected spin objects are predicted to show a variety of fascinating phenomena for possible skyrmion–antiskyrmion-based spintronics

Summary

Introduction

Skyrmions and antiskyrmions are topologically protected spin structures with opposite vorticities. Using LTEM imaging and superconducting quantum interference device—vibrating sample magnetometry (SQUID-VSM), we explore the dependence on applied oop magnetic field and temperature, which results in the formation and stabilization of different spin objects.

Results

Conclusion