Atomic and electronic structures of the SrVO₃-LaAlO₃ interface

The atomic and electronic structures at interfaces in thin films are typically different from the bulk and are vitally important in determining the physical properties of thin films. The interface between SrVO₃, chosen as a prototype for vanadium-based perovskite materials in this work, and LaAlO₃ substrate is investigated by scanning transmission electron microscopy, electron energy-loss spectroscopy, and theoretical multi-electron calculations. Extra electrons have been detected on the interface layer by comparing the energy-loss near-edge structures of V-L_3,2 edges to those from the film far from the interface. Monochromated EELS and theoretical calculations for SrVO₃, VO₂, and V₂O ₃ support this conclusion. The extra electrons appear to originate from a change in the local bonding configuration of V at the La-O terminated substrate surface as determined by Z-contrast imaging.