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TT: Fachverband Tiefe Temperaturen
TT 94: Low-Dimensional Systems: Oxide Hetero-Interfaces
TT 94.1: Talk
Thursday, April 3, 2014, 15:00–15:15, HSZ 204
Surface / interface interaction in LaAlO3/SrTiO3 heterostructures: an in-situ transport and photoemission study — •Philipp Scheiderer1, Florian Pfaff1, Judith Gabel1, Mihaela Gorgoi2, Michael Sing1, and Ralph Claessen1 — 1Physikalisches Institut and Röntgen Center for Complex Materials Systems, Universität Würzburg, Germany — 2Helmholtz Zentrum Berlin, Germany
Oxide heterostructures display many interesting phenomena, one example being the formation of a two-dimensional electron system (2DES) at the LaAlO3/SrTiO3 (LAO/STO) interface beyond a critical thickness of 4 monolayers (ML) of the polar LAO [1, 2]. An explanation for this behavior is the so-called electronic reconstruction. In this context it has recently been shown that polar adsorbates can enhance the conductivity of the 2DES [3]. Besides their electrostatic influence it was discussed that surface defects/adsorbates can also act as a charge reservoir [4]. To examine the impact of surface adsorbates on the 2DES we performed in-situ conductivity measurements and in-situ photoelectron spectroscopy (PES) on 6ML thick LAO/STO heterostructures exposed to a defined amount of water vapor. PES experiments indicate that water adsorbates induce additional charge carriers at titanium sites which are located at the interface. We correlate these spectroscopic findings with in-situ conductivity measurements.
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