  We study the dynamic coupling of magnons and phonons in single crystals of
Fe3GeTe2 (FGT) using inelastic scanning tunneling spectroscopy (ISTS) with an
ultra-low temperature scanning tunneling microscope. Inelastic scattering of
hot carriers off phonons or magnons has been widely studied using ISTS, and we
use it to demonstrate strong magnon-phonon coupling in FGT. We show a strong
interaction between magnons and acoustic phonons which leads to formation of
van Hove singularities originating in avoided level crossings and hybridization
between the magnonic and phononic bands in this material. We identify these
additional hybridization points in experiments and compare their energy with
density functional theory calculations. Our findings provide a platform for
designing the properties of dynamic magnon-phonon coupling in two-dimensional
materials.
