SKM 2023 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 4: Focus: Domains and Domainwalls in (Multi)Ferroic II

KFM 4.2: Talk

Tuesday, March 28, 2023, 09:30–09:50, POT 51

Real time polarization monitoring during growth for the design of artificial layered ferroelectrics — •Ipek Efe¹, Elzbieta Gradauskaite¹, Alexander Vogel², Marta D. Rossell², Manfred Fiebig¹, and Morgan Trassin¹ — ¹Department of Materials, ETH Zurich, Switzerland — ²Electron Microscopy Center, Empa, Switzerland

Increasing the complexity of unit cells of ferroelectric oxides beyond the standard perovskite building block supports exotic functionalities such as superconductivity, magnetoresistance, and ferroelectricity. However, integrating complex crystal structures into epitaxial design is challenging, and routes to precisely monitor the non-perovskite systems have yet to be established. Here, we directly access the polarization dynamics of the layered ferroelectric model system Aurivillius Bi₅FeTi₃O₁₅ films during growth using in-situ optical second harmonic generation (ISHG). We identify the characteristic Aurivillius antipolar ordering of the dipoles along the growth direction, which leads to an oscillating intensity of the ISHG signal during the layer-by-layer deposition. In combination with reflection high-energy electron diffraction monitoring, we show how the polarization orientation of the films consistently changes from out-of-plane during the growth of perovskite blocks, to fully in-plane upon the completion of the unit-cell with the fluorite-like (Bi₂O₂)²⁺ planes. We demonstrate how direct access to structure-dependent polarization dynamics during growth enables the development of novel layered systems incorporating various functional perovskite blocks into the Aurivillius structure.