Dresden 2017 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Thermoelectric Materials

DS 17.2: Talk

Monday, March 20, 2017, 18:00–18:15, CHE 89

Electronic and thermoelectric properties of polar LaNiO₃/SrTiO₃(001) superlattices — •Benjamin Geisler¹, Ariadna Blanca-Romero², and Rossitza Pentcheva¹ — ¹Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg, Germany — ²Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom

Advances in layer-by-layer fabrication techniques have made it possible to grow epitaxial transition metal oxide superlattices with atomic precision. We combine DFT+U calculations and Boltzmann transport theory to analyze the implications of the interface-dependent polar discontinuity in LaNiO₃/SrTiO₃(001) superlattices on the structural, electronic, and thermoelectric properties. While (LaO)⁺/(TiO₂)⁰ interfaces result in an n-type superlattice, (NiO₂)⁻/(SrO)⁰ interfaces lead to p-type doping. We find that significant octahedral tilts are induced in the SrTiO₃ region and that the La-Sr distances act as a fingerprint of the interface type. In contrast to the paradigmatic LaAlO₃/SrTiO₃ system, the electrostatic doping is mainly accommodated in the metallic NiO₂ layers. We explain the electronic structure within the SrTiO₃ band gap in terms of an orbital-selective quantization of Ni-3d-derived quantum well states. Complex cylindrical Fermi surfaces emerge which show a tendency towards nesting that depends on the interface polarity. Finally, we demonstrate that the thermoelectric response of our oxide superlattices can be selectively controlled by a targeted interface design.

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