Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Low-Dimensional Systems: Oxide Hetero-Interfaces
TT 8.3: Vortrag
Montag, 16. März 2015, 10:00–10:15, H 3010
Valence Band Electronic Structure and Band Alignment of LaAlO3/SrTiO3(111) Heterointerfaces — •J. Gabel1, P. Scheiderer1, M. Zapf1, P. Schütz1, C. Schlüter2, T.-L. Lee2, M. Sing1, and R. Claessen1 — 1Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg — 2Diamond Light Source, Didcot
As in the famous LaAlO3(LAO)/SrTiO3(STO) (001) a two-dimensional electron system (2DES) also forms at the interface between LAO and STO in (111) orientation. A distinct feature of the (111) interface is its peculiar real space topology. Each bilayer represents a buckled honeycomb lattice similar to graphene which is known theoretically to host various topologically non-trivial states. Bilayer STO in proximity to the interface can be regarded as a three-orbital generalization of graphene with enhanced electron correlations making it a promising candidate for the realization of strongly correlated topological phases. We have investigated the electronic structure of the LAO/STO (111) heterostructure in relation to the oxygen vacancy concentration which we can control by synchrotron light irradiation and oxygen dosing. With hard X-ray photoemission we study the core levels, whereas resonant soft X-ray photoemission is used to probe the interfacial valence band (VB) states. Two VB features are found: a peak at the Fermi level associated with the 2DES and in-gap states at higher binding energies attributed to oxygen vacancies. By varying the oxygen vacancy contribution we can tune the emergence of the VB states and engineer the interfacial band alignment.