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TT: Fachverband Tiefe Temperaturen

TT 20: Focus Session: The Nickel Age of Superconductivity: Cuprates Reloaded or Something New?

TT 20.7: Vortrag

Dienstag, 17. März 2020, 12:30–12:45, HSZ 03

Role of interface polarity in the electronic reconstruction of infinite-layer vs. perovskite nickelate films on SrTiO₃(001) — •Benjamin Geisler and Rossitza Pentcheva — Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg

Motivated by the recent observation of superconductivity in the infinite-layer nickelate NdNiO₂ on SrTiO₃(001) by Li et al. [1], we explore the effect of interface polarity on the electronic properties of NdNiO_n/SrTiO₃(001) and LaNiO_n/SrTiO₃(001) thin films (n = 2,3) by performing first-principles calculations including a Coulomb repulsion term. For infinite-layer nickelate films (n = 2), electronic reconstruction drives the emergence of a two-dimensional electron gas (2DEG) at the interface due to a strong occupation of the Ti 3d states. This effect is more pronounced than in the paradigmatic LaAlO₃/SrTiO₃(001) system and accompanied by a substantial reconstruction of the Fermi surface. We contrast our findings with results for the perovskite compounds (n = 3). Moreover, we analyze the topotactic reaction from a perovskite to an infinite-layer heterostructure and show why the reduction is confined to the nickelate film, whereas the SrTiO₃ substrate remains intact.
Funding by the DFG within TRR 80 (G3) is acknowledged.

[1] D. Li et al., Nature 572, 624 (2019)