title: Direct k-space mapping of the electronic structure in an oxide-oxide interface.
abstract: The interface between LaAlO(3) and SrTiO(3) hosts a two-dimensional electron system of itinerant carriers, although both oxides are band insulators. Interface ferromagnetism coexisting with superconductivity has been found and attributed to local moments. Experimentally, it has been established that Ti 3d electrons are confined to the interface. Using soft x-ray angle-resolved resonant photoelectron spectroscopy we have directly mapped the interface states in k space. Our data demonstrate a charge dichotomy. A mobile fraction contributes to Fermi surface sheets, whereas a localized portion at higher binding energies is tentatively attributed to electrons trapped by O vacancies in the SrTiO(3). While photovoltage effects in the polar LaAlO(3) layers cannot be excluded, the apparent absence of surface-related Fermi surface sheets could also be fully reconciled in a recently proposed electronic reconstruction picture where the built-in potential in the LaAlO(3) is compensated by surface O vacancies serving also as a charge reservoir.
authors.affiliation: Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Berner
authors.affiliation: Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Sing
authors.affiliation: Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Condensed Matter Science Division, Japan Atomic Energy Agency, SPring-8, Hyogo 679-5148, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Yasui
authors.affiliation: Condensed Matter Science Division, Japan Atomic Energy Agency, SPring-8, Hyogo 679-5148, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Saitoh
authors.affiliation: Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Yamasaki
authors.affiliation: Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nishitani
authors.affiliation: Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Sekiyama
authors.affiliation: Center for Electronic Correlations and Magnetism, Experimental Physics VI, Universität Augsburg, D-86135 Augsburg, Germany and Center for Electronic Correlations and Magnetism, Theoretical Physics III, Universität Augsburg, D-86135 Augsburg, Germany and Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Pavlenko
authors.affiliation: Center for Electronic Correlations and Magnetism, Experimental Physics VI, Universität Augsburg, D-86135 Augsburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kopp
authors.affiliation: Center for Electronic Correlations and Magnetism, Experimental Physics VI, Universität Augsburg, D-86135 Augsburg, Germany and Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Richter
authors.affiliation: Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Mannhart
authors.affiliation: Institute of Scientific & Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Suga
authors.affiliation: Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Claessen