Toward Functionalized Ultrathin Oxide Films: The Impact of Surface Apical Oxygen

Thin films of transition metal oxides open up a gateway to nanoscale electronic devices beyond silicon characterized by novel functionalities. While such are commonly prepared in an oxygen atmosphere, they typically considered be ideally terminated with the stoichiometric composition. Using prototypical correlated SrVO$_3$ as example, it is demonstrated that this idealized description overlooks essential ingredient: adsorbing at surface apical sites. The adatoms, which persist even ultrahigh vacuum environment, shown severely affect intrinsic structure oxide film. Their presence leads formation electronically dead layer but also alters band filling and electron correlations thin films. These findings highlight important take into account or -- mutatis mutandis specific configuration imposed capping predict behavior ultrathin near single unit-cell limit.