  The synthesis of stoichiometric and epitaxial pyrochlore iridate thin films
presents significant challenges yet is critical for unlocking experimental
access to novel topological and magnetic states. Towards this goal, we unveil
an in-situ two-stage growth mechanism that facilitates the synthesis of
high-quality oriented pyrochlore iridate thin films. The growth starts with the
deposition of a pyrochlore titanate as an active iso-structural template,
followed by the application of an in-situ solid phase epitaxy technique in the
second stage to accomplish the formation of single crystalline, large-area
films. This novel protocol ensures the preservation of stoichiometry and
structural homogeneity, leading to a marked improvement in surface and
interface qualities over previously reported methods. The success of this
synthesis approach is attributed to the application of directional laser-heat
annealing, which effectively reorganizes the continuous random network of ions
into a crystalline structure, as evidenced by our comprehensive analysis of the
growth kinetics. This new synthesis approach advances our understanding of
pyrochlore iridate film fabrication and opens a new perspective for
investigating their unique physical properties.
