Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 17: Poster Session: Correlated Electrons 1

TT 17.30: Poster

Montag, 1. April 2019, 15:00–18:30, Poster D

Exploring the potential gradient in the LaFeO₃/SrTiO₃ heterostructure by photoemission — •Martin Stübinger¹, Matthias Schmitt¹, Berengar Leikert¹, Pardeep Kumar Thakur², Tien-Lin Lee², Christoph Schlueter³, Michael Sing¹, and Ralph Claessen¹ — ¹Universität Würzburg, Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), 97074 Würzburg, Germany — ²Diamond Light Source Ltd., Didcot, Oxfordshire OX11 0DE, United Kingdom — ³DESY Photon Science, 22607 Hamburg, Germany

In the oxide heterostructure LaFeO₃/SrTiO₃ (LFO/STO), the polar discontinuity between the polar LFO and the non-polar STO leads to a potential gradient in the LFO film. As opposed to the famous LaAlO₃/SrTiO₃ system, the built-in potential is not compensated by an electron transfer to the interface and a two-dimensional electron system does not emerge. Indeed, photovoltaic effects making use of the potential gradient to separate electrons and holes have been observed. Furthermore, different terminations of the STO substrate have been reported to change the direction of the potential. Hence, we investigated TiO₂- as well as SrO-terminated substrates. Angle-dependent photoemission was used to determine the potential gradient across the LFO film. The enhanced probing depth of hard x-ray photoemission (HAXPES) gave also access to the substrate core levels to provide a complete picture of the band alignment at the interface. Our results show an upward bending of the substrate bands toward the interface and a thickness-dependent potential gradient in the LFO film.