Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Low-Dimensional Systems: Poster Session

TT 59.21: Poster

Mittwoch, 9. März 2016, 15:00–18:30, Poster D

Thermoelectric and spincaloric properties of epitaxial LaNiO₃/SrTiO₃ superlattices from first principles — •Benjamin Geisler^1,2, Ariadna Blanca-Romero³, and Rossitza Pentcheva² — ¹FRM II, Technische Universität München, 85748 Garching, Germany — ²Fakultät für Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany — ³Imperial College, London, United Kingdom

Modern layer-by-layer fabrication techniques make it possible to grow epitaxial oxide superlattices with atomic precision. By combining accurate DFT+U calculations to determine the atomic and electronic structure and Boltzmann transport theory we show how a targeted design of the interface composition can be used to optimize the thermoelectric and/or spincaloric properties of LaNiO₃/SrTiO₃(001) superlattices. A TiO₂/LaO interface induces n-type doping, and a (potentially highly spin-polarized) charge current arises solely in-plane in the NiO₂ layers. The out-of-plane resistance is high, since the SrTiO₃ layers act as tunneling barriers. In contrast, a NiO₂/SrO interface leads to p-type doping. In this case, also the valence band of SrTiO₃ contributes to the transmission, thereby reducing the out-of-plane resistance significantly. Besides this doping effect we find that the interface composition influences the electronic band structure, which leads to a nontrivial behavior of the Seebeck coefficient.

Funding by the DFG within TRR 80 (G3 and G8) is acknowledged.