  Magnetism in two-dimensional (2D) van der Waals (vdW) materials has lately
attracted considerable attention from the point of view of both fundamental
science and device applications. Obviously, establishing the detailed and solid
understanding of their magnetism is the key first step toward various
applications. Although $\mathrm{Fe_3GeTe_2}$ is a representative ferromagnetic
(FM) metal in this family, many aspects of its magnetic and electronic
behaviors still remain elusive. Here, we report our new finding that
$\mathrm{Fe_3GeTe_2}$ is a special type of correlated metal known as 'Hund
metal'. Furthermore, we demonstrate that Hund metallicity in this material is
quite unique by exhibiting remarkable site-dependence of Hund correlation
strength, hereby dubbed 'site-differentiated Hund metal'. Within this new
picture, many of previous experiments can be clearly understood including the
ones that were seemingly contradictory to one another.
