  Motivated by the search for design principles of rare-earth-free strong
magnets, we present a study of electronic structure and magnetic properties of
the ferromagnetic metal Fe3GeTe2 within local density approximation (LDA) of
the density functional theory, and its combination with dynamical mean-field
theory (DMFT). For comparison to these calculations, we have measured magnetic
and thermodynamic properties as well as X-ray magnetic circular dichroism and
the photoemission spectrum of single crystal Fe3GeTe2. We find that the
experimentally determined Sommerfeld coefficient is enhanced by an order of
magnitude with respect to the LDA value. This enhancement can be partially
explained by LDA+DMFT. In addition, the inclusion of dynamical electronic
correlation effects provides the experimentally observed magnetic moments, and
the spectral density is in better agreement with photoemission data. These
results establish the importance of electronic correlations in this
ferromagnet.
