  We report on the growth of epitaxial Sr2RuO4 films using a hybrid molecular
beam epitaxy approach in which a volatile precursor containing RuO4 is used to
supply ruthenium and oxygen. The use of the precursor overcomes a number of
issues encountered in traditional MBE that uses elemental metal sources.
Phase-pure, epitaxial thin films of Sr2RuO4 are obtained. At high substrate
temperatures, growth proceeds in a layer-by-layer mode with intensity
oscillations observed in reflection high-energy electron diffraction. Films are
of high structural quality, as documented by x-ray diffraction, atomic force
microscopy, and transmission electron microscopy. The method should be suitable
for the growth of other complex oxides containing ruthenium, opening up
opportunities to investigate thin films that host rich exotic ground states.
