Regensburg 2022 – scientific programme

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SYQM: Complexity and Topology in Quantum Matter

SYQM 1: Complexity and Topology in Quantum Matter

SYQM 1.5: Invited Talk

Friday, September 9, 2022, 11:45–12:15, H1

Spectroscopic Studies of the Topological Magnon Band Structure in a Skyrmion Lattice — •Markus Garst — Karlsruhe Institute of Technology

When magnons propagate across a non-collinear magnetic texture, they collect a Berry phase that can be interpreted as the flux of a synthetic orbital magnetic field. The magnon thus experiences a synthetic Lorentz force that bends the quasi-classical trajectories of the magnons. For a magnetic skyrmion lattice, the average synthetic field is finite such that the magnons are confined to cyclotron orbits of the corresponding magnon Landau levels. This is reflected in a magnon band structure with finite Chern numbers. Here, we report on a series of spectroscopic studies of this band structure using various techniques that allow to probe different regimes in energy-momentum space: magnetic resonance spectroscopy [1], spin-wave spectroscopy [2], inelastic neutron scattering [3] and Brillouin light scattering [4,5]. These techniques have been applied to various cubic chiral magnets like MnSi, FeCoSi and Cu2OSeO3, that are well described by a universal effective continuum theory parametrized by a few parameters only. The combined data from all techniques are found to be in quantitative agreement with theory.

[1] R. Takagi et al. Phys. Rev. B 104, 144410 (2021). [2] S. Seki et al. Nat. Commun. 11, 256 (2020). [3] T. Weber et al. Science 375, 1025 (2022). [4] N. Ogawa et al. PNAS 118, e2022927118 (2021). [5] P. Che et al. unpublished.