SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 35: Skyrmions III
MA 35.5: Vortrag
Donnerstag, 30. März 2023, 10:30–10:45, HSZ 04
Nonlinear dynamics of skyrmion strings — •Volodymyr Kravchuk1,2 and Markus Garst1 — 1Institut für Theoretische Festkörperphysik, Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany — 2Bogolyubov Institute for Theoretical Physics of the National Academy of Sciences of Ukraine, 03143 Kyiv, Ukraine
A skyrmion core, percolating the magnet volume, forms a skyrmion string – the topological Dirac string-like object. Here we analyze the nonlinear dynamics of a skyrmion string in a low-energy regime by means of the collective variables approach generalized for the case of strings. Using the perturbative method of multiple scales (both in space and time), we show that the weakly nonlinear dynamics of the translational mode propagating along the string is captured by the Nonlinear Schrödinger equation of the focusing type. As a result, the fundamental helix-shaped “planar-wave” solution experiences modulational instability, which leads to the formation of cnoidal waves. Both types of cnoidal waves, dn- and cn-waves, as well as the separatrix soliton solution [1], are confirmed by the micromagnetic simulations. Beyond the class of the traveling-wave solutions, we found Ma-breather propagating along the string. Finally, we proposed a generalized approach, which enables one to describe nonlinear dynamics of the modes of different symmetries, radially symmetrical, elliptical, etc.
[1] V.P. Kravchuk, U.K. Rößler, J. van den Brink, M. Garst, Phys. Rev. B 102, 220408(R) (2020).