In-situ fabrication of pyrochlore epitaxial thin film and heterostructures*

We report on the successful in-situ fabrication of a variety (111) oriented thin films with pyrochlore structure R2Ir2O7 (R is rare-earth) by a hybrid approach utilizing solid phase epitaxy and layer-by-layer pulsed laser deposition. Specifically, we report on developing an entirely in-situ annealing protocol, which is superior to the conventional ex-situ routine that requires multi-hour annealing to stabilize the proper pyrochlore structure. In addition, the excellent morphological quality of the films was verified by x-ray diffraction, reflectivity, reciprocal space mapping, XPS, and TEM, demonstrating their high crystallinity with a pure pyrochlore phase, smooth surface, proper electronic structure, and an expected epitaxial relation to the substrate. Our findings open a new solution to the long-standing challenge of the growth of pyrochlore single-crystalline thin films and heterostructures based on them. Furthermore, this all-in-situ approach provides new opportunities for applying surface-sensitive probes.