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TT: Fachverband Tiefe Temperaturen

TT 94: Low-Dimensional Systems: Oxide Hetero-Interfaces

TT 94.1: Vortrag

Donnerstag, 3. April 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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