Manipulating the Polar mismatch at LaNiO3/SrTiO3 (111) Interface

Heteroepitaxial growth of transition-metal oxide films on the open (111) surface of SrTiO3 results in significant restructuring due to the polar mismatch. Monitoring the structural and composition on an atomic scale of LaNiO3/SrTiO3 (111) interface as a function of processing conditions has enabled the avoidance of the expected polar catastrophe. Using atomically resolved transmission electron microscopy and spectroscopy as well as Low energy electron diffraction, the structure of the thin film, from interface to the surface, has been studied. In this paper, we show that the proper processing can lead to a structure that is ordered, coherent with the substrate without intermediate structural phase. Angle-resolved X-ray photoemission spectroscopy shows that the oxygen content of thin films increases with the film thickness, indicating that the polar mismatch is avoided by the presence of oxygen vacancies.