Multipole magnons in topological skyrmion lattices resolved by cryogenic Brillouin light scattering microscopy

P Che, R Ciola, M Garst, V Kravchuk, PR Baral… - arXiv preprint arXiv …, 2024 - arxiv.org
P Che, R Ciola, M Garst, V Kravchuk, PR Baral, A Magrez, H Berger, T Schönenberger…
arXiv preprint arXiv:2404.14314, 2024arxiv.org
Non-collinear magnetic skyrmion lattices provide novel magnonic functionalities due to their
topological magnon bands and asymmetric dispersion relations. Magnon excitations with
intermediate wavelengths comparable to inter-skyrmion distances are particularly interesting
but largely unexplored so far due to experimental challenges. Here, we report the detection
of such magnons with wavevectors q $\simeq $48 rad/um in the metastable skyrmion lattice
phase of the bulk chiral magnet Cu $ _2 $ OSeO $ _3 $ using micro-focused Brillouin light …
Non-collinear magnetic skyrmion lattices provide novel magnonic functionalities due to their topological magnon bands and asymmetric dispersion relations. Magnon excitations with intermediate wavelengths comparable to inter-skyrmion distances are particularly interesting but largely unexplored so far due to experimental challenges. Here, we report the detection of such magnons with wavevectors q 48 rad/um in the metastable skyrmion lattice phase of the bulk chiral magnet CuOSeO using micro-focused Brillouin light scattering microscopy. Thanks to its high sensitivity and broad bandwidth we resolved various excitation modes of a single skyrmion lattice domain over a wide magnetic field regime. Besides the known modes with dipole character, quantitative comparison of frequencies and spectral weights to theoretical predictions enabled the identification of a quadrupole mode and observation of signatures which we attribute to a decupole and a sextupole mode. Our combined experimental and theoretical work highlights that skyrmionic phases allow for the design of magnonic devices exploiting topological magnon bands.
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