  We report on the synthesis of ultrathin films of highly distorted EuNiO3
(ENO) grown by interrupted pulse laser epitaxy on YAlO3 (YAO) substrates.
Through mapping the phase space of nickelate thin film epitaxy, the optimal
growth temperatures were found to scale linearly with the Goldschmidt tolerance
factor. Considering the gibbs energy of the expanding film, this empirical
trend is discussed in terms of epitaxial stabilization and the escalation of
the lattice energy due to lattice distortions and decreasing symmetry. These
findings are fundamental to other complex oxide perovskites, and provide a
route to the synthesis of other perovskite structures in ultrathin-film form.
