SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 26: Non-Skyrmionic Magnetic Textures II
MA 26.5: Vortrag
Mittwoch, 29. März 2023, 11:00–11:15, HSZ 401
Stability of Hopfions in Bulk Magnets with Competing Exchange Interactions — •Moritz Sallermann1,2,3, Hannes Jónsson3, and Stefan Blügel1 — 1PGI-1 and IAS-1, Forschungszentrum Jülich and JARA, Jülich, Germany — 2Department of Physics, RWTH Aachen, Aachen, Germany — 3Science Institute and Faculty of Physical Sciences, University of Iceland, Reykjavík, Iceland
Magnetic hopfions are three-dimensional topological solitons, characterised by the Hopf number. Based on a micromagnetic model, the existence of free moving hopfions has been predicted in certain magnets with competing exchange interactions [1]. However, physical realisations of free moving hopfions in bulk magnets have so far been elusive. Here, we consider an effective spin lattice Heisenberg model with competing exchange interactions and computationally study the stability of small toroidal hopfions with unity Hopf number by finding first-order saddle points representing the transition state for the decay of hopfions to the ferromagnetic ground state, via the formation of two coupled Bloch points. We show that the energy barriers can reach substantial heights and are largely determined by the size of the hopfions. The saddle point methods are discussed.
We acknowledge funding by DFG through SPP 2137 and SFB 1238, through the Helmholtz-RSF Joint Research Group “TOPOMANN”, the ERC under the EU Horizon 2020 research and innovation programme (no. 856538) and the Icelandic Research Fund (no. 185405-053).
[1] F. N. Rybakov et al., Apl. Mater. 10, 111113 (2022)