Short-wave magnons with multipole spin precession detected in the topological bands of a skyrmion lattice

Ping Che; Riccardo Ciola; Markus Garst; Volodymyr Kravchuk; Priya R. Baral; Arnaud Magrez; Helmuth Berger; Thomas Schönenberger; Henrik M. Rønnow; Dirk Grundler

doi:10.1038/s43246-025-00858-4

paper

Short-wave magnons with multipole spin precession detected in the topological bands of a skyrmion lattice

arXiv:2404.14314 · doi:10.1038/s43246-025-00858-4

Abstract

Topological magnon bands enable uni-directional edge transport without backscattering, enhancing the robustness of magnonic circuits and providing a novel platform for exploring quantum transport phenomena. Magnetic skyrmion lattices, in particular, host a manifold of topological magnon bands with multipole character and non-reciprocal dispersions. These modes have been explored already in the short and long wavelength limit, but previously employed techniques were unable to access intermediate wavelengths comparable to inter-skyrmion distances. Here, we report the detection of such magnons with wavevectors $∣ q ∣ ≃ 48$ rad $μ$ m $^{- 1}$ in the metastable skyrmion lattice phase of the bulk chiral magnet Cu $_{2}$ OSeO $_{3}$ using Brillouin light scattering microscopy. Thanks to its high sensitivity and broad bandwidth various multipole excitation modes could be resolved over a wide magnetic field regime. Besides the known counterclockwise, breathing and clockwise modes with dipole character, quantitative comparison of frequencies and spectral weights to theoretical predictions enabled the additional identification of a quadrupole mode and, possibly, a sextupole mode. Our work highlights the potential of skyrmionic phases for the design of magnonic devices exploiting topological magnon states at GHz frequencies.

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Topological transition in spectrum of skyrmion crystal with uniaxial anisotropy