Skyrmion States in Disk Geometry

Thomas Brian Winkler, Kai Litzius, Andrea de Lucia, Markus Weißenhofer, Hans Fangohr, and Mathias Kläui
Phys. Rev. Applied 16, 044014 – Published 11 October 2021

Abstract

In this work, we explore the stability of magnetic skyrmions confined in a disk geometry by analyzing how to switch a skyrmionic state in a circular disk into a uniformly magnetized state when applying an external magnetic field. The technologically highly relevant energy barrier between the skyrmion state and the uniformly magnetized state is a key parameter needed for lifetime calculations. In an infinite sample, this relates to the out-of-plane rupture field against the skyrmion-core direction, while in confined geometries the topological charge can also be changed by interactions with the sample edges. We find that annihilating a skyrmion with an applied field in the direction of the core magnetization—we call this expulsion—the energy barrier to the uniform state is generally around one order of magnitude lower than the annihilation via the rupture of the core in the disk center, which is observed when the applied field is acting in the direction opposite to the core magnetization. For the latter case a Bloch point (BP) needs to be nucleated to change the topological charge to zero. We find that the former case can be realistically calculated using micromagnetic simulations but that the annihilation via rupture, involving a Bloch point, needs to be calculated with the Heisenberg model because the high magnetization gradients present during the annihilation process cannot be accurately described within the micromagnetic framework.

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  • Received 16 December 2020
  • Revised 31 July 2021
  • Accepted 22 September 2021

DOI:https://doi.org/10.1103/PhysRevApplied.16.044014

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Thomas Brian Winkler1,*, Kai Litzius2, Andrea de Lucia1, Markus Weißenhofer3, Hans Fangohr4,5,6,†, and Mathias Kläui1,‡

  • 1Institute of Physics, Johannes Gutenberg Universtät, Staudinger Weg 7, Mainz 55122, Germany
  • 2Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
  • 3Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, Konstanz 78464, Germany
  • 4Max-Planck Institute for Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
  • 5European XFEL, Holzkoppel 4, Schenefeld 22869, Germany
  • 6University of Southampton, Southampton SO17 1BJ, United Kingdom

  • *twinkler@uni-mainz.de
  • hans.fangohr@mpsd.mpg.de
  • Klaeui@uni-mainz.de

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Vol. 16, Iss. 4 — October 2021

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