Manipulating the polar mismatch at the LaNiO3/SrTiO3 (111) interface

Heteroepitaxial growth of transition-metal oxide films on the open (111) surface of SrTi O-3 results in significant restructuring due to the polar mismatch. Monitoring the structure and composition on an atomic scale of LaNi O-3 / SrTi O-3 (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. Here, we show that the proper processing can lead to a structure that is ordered, coherent with the substrate without intermediate structural phase. Using angle-resolved x-ray photoemission spectroscopy we show that the oxygen content of thin films increases with the film thickness, which indicates that the polar mismatch is avoided by the presence of oxygen vacancies.