Dresden 2026 – scientific programme
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DS: Fachverband Dünne Schichten
DS 6: Thin Oxides and Oxide Layers
DS 6.2: Talk
Tuesday, March 10, 2026, 10:00–10:15, REC/C213
Atomic Scale Insights into the Polymorphism of Ruddlesden-Popper Nickelates and Titanates — Shihao Wei1, Stefania Baronio2, Bruce Davidson2, Ke Zou2, and •Nicolas Bonmassar1 — 1Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenberstr. 3, 70569, Germany — 2Quantum Matter Institute, University of British Columbia, Vancouver, Canada
Ruddlesden-Popper (RP) oxides provide an ideal platform for investigating coupled structural and electronic phenomena, as subtle variations in layering and cation coordination can significantly alter their functional properties. Using oxide molecular beam epitaxy, we can grow distinct nickelate and titanate RP phases with atomic-layer precision, demonstrating the controlled stabilization of distinct polymorphs by tuning the rock-salt and perovskite layers. Advanced scanning transmission electron microscopy provides insights into the resulting structures at an atomic scale, enabling the direct identification of the respective polymorph and the characterization of extended defects, such as stacking faults. By correlating local structure with electronic properties, we can establish clear structure-property relationships across all samples. Electron energy-loss and energy-dispersive X-ray spectroscopy reveal the differences in transition-metal oxidation states, defect density and oxygen orbital occupation between the different RP phases and polymorphs. Our results highlight how precise control of the individual layers leads to the control over the polymorphs in RP nickelates and titanates.
Keywords: High Tc Superconducting Nickelates; Polymorphism; Scanning Transmission Electron Microscopy