  Fe3GeTe2 has emerged as one of the most fascinating van der Waals crystals
due to its two-dimensional (2D) itinerant ferromagnetism, topological nodal
lines and Kondo lattice behavior. However, lattice dynamics, chirality of
phonons and spin-phonon coupling in this material, which set the foundation for
these exotic phenomena, have remained unexplored. Here we report the first
experimental investigation of the phonons and mutual interactions between spin
and lattice degrees of freedom in few-layer Fe3GeTe2. Our results elucidate
three prominent Raman modes at room temperature: two A1g({\Gamma}) and one
E2g({\Gamma}) phonons. The doubly degenerate E2g({\Gamma}) mode reverses the
helicity of incident photon, indicating the pseudo-angular momentum and
chirality. Through analysis of temperature-dependent phonon energies and
lifetimes, which strongly diverge from the anharmonic model below Curie
temperature, we determine the spin-phonon coupling in Fe3GeTe2. Such
interaction between lattice oscillations and spin significantly enhances the
Raman susceptibility, allowing us to observe two additional Raman modes at the
cryogenic temperature range. In addition, we reveal laser radiation induced
degradation of Fe3GeTe2 in ambient conditions and the corresponding Raman
fingerprint. Our results provide the first experimental analysis of phonons in
this novel 2D itinerant ferromagnet and their applicability for further
fundamental studies and application development.
