Markus Garst

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We give an overview of our recent work on the dynamics of magnetic skyrmions. In bulk chiral magnets two-dimensional skyrmion textures extend in the third direction forming strings and skyrmion string lattices. These lattices exhibit various excitations modes. Magneto-optic and magneto-elastic couplings allow to access excitation modes with multipole character that are inaccessible with magnetic resonance spectroscopy. Brillouin light scattering is able to resolve a quadrupole mode [1]. The magneto-elastic coupling leads to a hybridization of ultrasound with various excitation modes and, in addition, it leads to a phason gap due to a distortion of the atomic crystal [2]. Going beyond linear dynamics, we demonstrate that a single skyrmion string supports solitary waves similar to vortex filaments in fluids [3]. Finally, we discuss the quantum dynamics of skyrmions and show that it is governed by a dipole conservation law associated with the topological charge. As a result, the mobility of isolated quantum skyrmions is constrained resembling the phenomenology of fracton theories [4].

[1] P. Che, R. Ciola, M. Garst, V. Kravchuk, P.R. Baral, A. Magrez, H. Berger, T. Schöneberger, H. M.
Rønnow, and D. Grundler, Communication Materials 6, 139 (2025).
[2] R. Ciola, PhD Thesis, Karlsruhe Institute of Technology.
[3] P. Kravchuk, U. Rößler, J. van den Brink, and M. Garst, Phys. Rev. B 102, 220408(R) (2020).
[4] S. Sorn, J. Schmalian, and M. Garst, arXiv:2412.16284, Physical Review X in press.

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Karlsruhe Institute of Technology
PH2
Contact: Achim Rosch / Matteo Cacco