Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Low-Dimensional Systems: Poster Session
TT 59.19: Poster
Mittwoch, 9. März 2016, 15:00–18:30, Poster D
Oxygen vacancies at the spinel/perovskite γ-Al2O3/SrTiO3 heterointerface probed by resonant photoelectron spectroscopy — •Philipp Schütz1, Florian Pfaff1, Michael Zapf1, Judith Gabel1, Lenart Dudy1, Götz Berner1, Yunzhong Chen2, Nini Pryds2, Christoph Schlüter3, Tien-Lin Lee3, Michael Sing1, and Ralph Claessen1 — 1Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Würzburg, Germany — 2Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, Denmark — 3Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, United Kingdom
The spinel/perovskite heterointerface between the band insulators γ-Al2O3 and SrTiO3 hosts a two-dimensional electron system (2DES) with exceptionally high electron mobility. Soft x-ray resonant photoelectron spectroscopy at the Ti L absorption edge is used to probe the Ti 3d derived interface states. Marked differences in the resonance behavior are found for the SrTiO3 valence band and the different interface states, which are observed in the band gap of SrTiO3. A comparison to x-ray absorption spectra of Ti 3d0 and Ti 3d1 systems reveals the presence of different types of electronic states with Ti 3d character, i.e., oxygen vacancy induced, trapped in-gap states and itinerant states contributing to the 2DES. Exposure to low doses of oxygen during irradiation allows for the reversible manipulation of the oxygen stoichiometry, thus revealing the presence of an oxygen vacancy-induced state, which is characteristic for this spinel/perovskite interface.