Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 72: Low-Dimensional Systems: Poster Session
TT 72.8: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Resonant photoelectron spectroscopy of γ-Al2O3/SrTiO3 heterostructures — •Philipp Schütz1, Florian Pfaff1, Michael Zapf1, Judith Gabel1, Lenart Dudy1, Götz Berner1, Yunzhong Chen2, Nini Pryds2, Victor Rogalev3, Vladimir Strocov3, Christoph Schlüter4, Tien-Lin Lee4, 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 — 3Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland — 4Diamond Light Source Ltd., 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. Furthermore, exposure to low doses of oxygen during irradiation allows for the controlled and reversible manipulation of the interfacial electronic structure, i.e., the in-gap state intensity and the valence band offset between SrTiO3 and γ-Al2O3.