Mapping electronic reconstruction at the metal-insulator interface in LaVO 3 /SrVO 3 heterostructures
Résumé
A (LaVO3)6/(SrVO3)3 superlattice is studied with a combination of sub-Å resolved scanning transmission electron microscopy and monochromated electron energy-loss spectroscopy. The V oxidation state is mapped with atomic spatial resolution enabling us to investigate electronic reconstruction at the LaVO3/SrVO3 interfaces. Surprisingly, asymmetric charge distribution is found at adjacent chemically symmetric interfaces. The local structure is proposed and simulated with a double channeling calculation which agrees qualitatively with our experiment. We demonstrate that local strain asymmetry is the likely cause of the electronic asymmetry of the interfaces. The electronic reconstruction at the interfaces extends much further than the chemical composition, varying from 0.5 to 1.2 nm. This distance corresponds to the length of charge transfer previously found in the (LaVO3)m/(SrVO3)n metal/insulating and the (LaAlO3)m/(SrTiO3)n insulating/insulating interfaces.