Synthesis and electronic properties of epitaxial SrNiO3/ SrTiO3 superlattices

We report the deposition and characterization of a set of high-quality (SrNiO3)1/(SrTiO3)n superlattices using oxide molecular beam epitaxy. We demonstrate that one unit cell of SrNiO3 can be stabilized as a perovskite in these structures and that there is no charge transfer across the heterointerface. Detailed spectroscopy data analysis indicates that holes are confined to the SrNiO3 unit cells, resulting in a Ni valence between 3 and 4. Hole hopping conductivity is observed in the n=1 superlattice but is strongly suppressed along the c-axis direction for n=3 and 5, resulting in the insulating behavior in the latter. Our study will inspire the epitaxial synthesis of (SrNiO3)1/(RNiO3)n superlattices, as measurements of their properties could open a platform for studying nickelate-based superconductors.