Regensburg 2025 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 29: Skyrmions II
MA 29.9: Vortrag
Mittwoch, 19. März 2025, 17:15–17:30, H20
The dynamics of skyrmion shrinking — •Frederik Austrup1, Wolfgang Häusler2, Michael Lau1, and Michael Thorwart1 — 1I. Institut für Theoretische Physik, Universität Hamburg — 2Institut für Physik, Universität Augsburg
When magnetic skyrmions decay, their size in real space decreases in a finite time before they eventually collapse. We derive a continuum model to describe the shrinking behavior of skyrmions before they collapse. Using the Landau-Lifshitz-Gilbert equation and the time derivative of the vectorfield, we find a set of coupled nonlinear ordinary differential equation for the time dependent skyrmion radius and helicity. In particular, we use a triangular-shaped skyrmion profile of its polar angle. Contrary to the commonly expected simple exponential decrease in size, we reveal a more complicated time dependence, where the time-dependent radius crosses over from an exponential decay towards a square root decrease, ∼ (t − tc)1/2, near a critical time tc at which it collapses. This critical time is found to depend logarithmically on the lattice constant. Additionally, we present studies examining the interplay between the shrinking and a transformation through different skyrmion configurations, depending on the various system parameters. The findings are accompanied by numerical studies, supporting the predictions from the theoretical continuum model.
Keywords: Skyrmion; Ferromagnet; Skyrmion Shrinking; Skyrmion Collapse; Breathing Modes