Determination of the surface and interface phase shifts in metallic quantum well structures of perovskite oxides

We propose an experimental approach to extract separately the surface and interface phase shift of standing waves in metallic quantum well (QW) structures composed of isostructural perovskite oxides. The "asymmetric" vacuum/SrVO sub(3)/SrTiO sub(3) and "symmetric" SrTiO sub(3)/SrVO sub(3)/SrTiO sub(3) QW structures are fabricated in an epitaxial multilayer form. Using these metallic QW structures, the phase shifts at the surface (vacuum/SrVO sub(3)) and interface (SrTiO sub(3)/SrVO sub(3)) are successfully obtained by analyzing a thickness series of angle-resolved photoemission spectra. The difference of the phase shift between the two boundaries reveals that nearly ideal quantum confinement is achieved at the interface, indicating that a SrTiO sub(3) layer acts as a useful potential barrier.