  In recent years, two-dimensional van der Waals materials have emerged as an
important platform for the observation of long-range ferromagnetic order in
atomically thin layers. Although heterostructures of such materials can be
conceived to harness and couple a wide range of magneto-optical and
magneto-electrical properties, technologically relevant applications require
Curie temperatures at or above room-temperature and the ability to grow films
over large areas. Here we demonstrate the large-area growth of single-crystal
ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using
molecular beam epitaxy. Magnetic measurements show the persistence of soft
ferromagnetism up to room temperature, with a Curie temperature of 293 K, and a
weak out-of-plane magnetocrystalline anisotropy. Surface, chemical, and
structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te
stoichiometric elementary composition, and single crystalline character of the
films.
