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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 28: Focus Session: (Multi-)Ferroic States IV

KFM 28.2: Talk

Thursday, March 21, 2024, 15:30–15:50, EMH 225

Nanoscale electrostatic control of polarization in ferroelectric thin films using lattice chemistry — •Ipek Efe¹, Alexander Vogel², William S. Huxter¹, Elzbieta Gradauskaite¹, Christian L. Degen¹, Marta D. Rossell², Manfred Fiebig¹, and Morgan Trassin¹ — ¹ETH Zurich — ²Empa, Switzerland

Nanoscale electrostatic control of oxide interfaces enables functionalities beyond the realm of the bulk material, including superconductivity, multiferroicity, and topological properties. Here, by exploiting spontaneously forming charged interfaces in layered materials, we control the electrostatic boundary conditions in ferroelectric oxide heterostructures. Using in-situ optical second harmonic generation during the growth of layered Aurivillius Bi₅FeTi₃O₁₅ films, we correlate, in real-time, the stacking of highly charged fluorite-like (Bi₂O₂)²⁺ layers with the formation of the out-of-plane antipolar ordering of electric dipoles in the unit-cell. Next, we insert multiferroic BiFeO₃ into the Aurivillius scaffold and show that the resulting charged layering stabilizes the ferrielectric-like ordering of the electric dipoles. Our work brings the use of polarizing charged layers of layered oxides as an additional degree of freedom towards the design of technologically relevant electric dipole orderings in epitaxial thin films.

Keywords: Ferroelectric thin films; Layered ferroelectrics; Polarization engineering; Aurivillius; Polarization evolution