  The first examples of single crystal epitaxial thin films of a high entropy
perovskite oxide are synthesized. Pulsed laser deposition is used to grow the
configurationally disordered ABO3 perovskite, Ba(Zr0.2Sn0.2Ti0.2Hf0.2Nb0.2)O3,
epitaxially on SrTiO3 and MgO substrates. X-ray diffraction and scanning
transmission electron microscopy demonstrate that the films are single phase
with excellent crystallinity and atomically abrupt interfaces to the underlying
substrates. Atomically-resolved electron energy loss spectroscopy mapping shows
a uniform and random distribution of all B-site cations. The ability to
stabilize perovskites with this level of configurational disorder offers new
possibilities for designing materials from a much broader combinatorial cation
pallet while providing a fresh avenue for fundamental studies in strongly
correlated quantum materials where local disorder can play a critical role in
determining macroscopic properties.
