Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 80: Low-Dimensional Systems: Oxide Hetero-Interfaces

TT 80.2: Vortrag

Freitag, 24. März 2017, 09:45–10:00, HSZ 103

Electronic and orbital reconstruction in La₂CuO₄/LaNiO₃ superlattices — •Benjamin Geisler¹, Friederike Wrobel², Eva Benckiser², Bernhard Keimer², and Rossitza Pentcheva¹ — ¹Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg, Germany — ²Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany

Artificial transition metal oxide heterostructures can display exotic characteristics notably different from their bulk components. In a combined experimental and theoretical study we report on superlattices formed by the parent compound of cuprate superconductors La₂CuO₄ (d⁹) and the correlated metal LaNiO₃ (formal d⁷). TEM reveals high quality (La₂CuO₄)_N/(LaNiO₃)_M(001) structures (N=2,3; M=4). Density functional calculations with on-site correlation show that the electrostatic doping due to an extra LaO layer at the interface is exclusively accommodated in the LaNiO₃ region, while the electronic and magnetic properties of the La₂CuO₄ part remain bulk-like. This is consistent with our Ni L-edge XAS measurements which provide evidence for Ni²⁺ in addition to the expected Ni³⁺. In addition, a charge disproportionation arises at the Ni sites that drives a metal-to-insulator transition in the interface layers and is reflected also by the magnetic moments and the octahedral volumes. The simulations show a preference for a layerwise AFM order of the Ni moments but with a net total moment, which agrees with our XMCD measurements. A Ni orbital polarization of ∼ 6% in favor of 3d_z² arises near the interfaces.

Funding by the DFG within TRR 80 (G1, G3, G8) is acknowledged.