  TbMn6Sn6 is a metallic ferrimagnet that displays signatures of band topology
arising from a combination of uniaxial ferromagnetism and spin-orbit coupling
within its Mn kagome layers. Whereas the low energy magnetic excitations can be
described as collective spin waves using a local moment Heisenberg model,
sharply defined optical and flat-band collective magnon modes are not observed.
In their place, we find overdamped chiral and flat-band spin correlations that
are localized to hexagonal plaquettes within the kagome layer.
