SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 50: Focus Session: Superconducting Nickelates II
TT 50.3: Vortrag
Donnerstag, 30. März 2023, 15:30–15:45, HSZ 03
Thickness-dependent interface polarity in infinite-layer nickelate superlattices — •Chao Yang1, Roberto A. Ortiz1, Yi Wang2, Wilfried Sigle1, Hongguang Wang1, Eva Benckiser1, Bernhard Keimer1, and Peter A. van Aken1 — 1Max Planck Institute for Solid State Research, Stuttgart, 70569, Germany — 2Center for Microscopy and Analysis, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, P.R. China
The interface polarity plays a vital role in the physical properties of oxide hetero-interfaces, since it can enforce a reconstruction of the electronic and atomic structure. In the recently discovered superconducting nickelate thin films, interfacial effects could play an important role. This motivated our investigation of the electronic and atomic structure at the atomic scale at interfaces of infinite-layer nickelate thin films. Using four-dimensional scanning transmission electron microscopy (4D-STEM) and electron energy-loss spectroscopy (EELS), we systematically studied the effects of oxygen distribution and site occupancy, polyhedral distortion, elemental intermixing, as well as dimensionality on interface properties of infinite-layer NdNiO2/SrTiO3 superlattices. The oxygen intensity and distribution maps show the local symmetry change from octahedral to square planar induced by the reduction process and a gradual change of the oxygen content in the nickelate layers. Remarkably, we demonstrate spatially controlled interface polarity with accompanying interface reconstructions. Our results provide insights to understand the effects of polarity and dimensionality on the interface properties of infinite-layer nickelates.