Bulk- and Surface-Sensitive High-Resolution Photoemission Study of Two Mott-Hubbard Systems:SrVO3andCaVO3

We study the electronic structure of Mott-Hubbard systems ${\mathrm{SrVO}}_{3}$ and ${\mathrm{CaVO}}_{3}$ with bulk and surface-sensitive high-resolution photoemission spectroscopy, using a vacuum ultraviolet laser, synchrotron radiation, and a discharge lamp ($h\ensuremath{\nu}=7--21\text{ }\text{ }\mathrm{eV}$). A systematic suppression of the density of states (DOS) within $\ensuremath{\sim}0.2\text{ }\text{ }\mathrm{eV}$ of the Fermi level (${E}_{\mathrm{F}}$) is found on decreasing photon energy, i.e., on increasing bulk sensitivity. The coherent band in ${\mathrm{SrVO}}_{3}$ and ${\mathrm{CaVO}}_{3}$ is shown to consist of surface and bulk-derived features, separated in energy. The stronger distortion on surface of ${\mathrm{CaVO}}_{3}$ compared to ${\mathrm{SrVO}}_{3}$ leads to a higher surface metallicity in the coherent DOS at ${E}_{\mathrm{F}}$, consistent with recent theory.