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Séminaire - Elzbieta Gradauskaite

Vendredi 4 Novembre 2022 à 14h00, Elzbieta Gradauskaite (ETH Zurich) donnera un séminaire intitulée : "Layered ferroelectrics for oxide electronics".
Résumé :
Material surfaces encompass structural and chemical discontinuities that often lead to the loss of the property of interest in the so-called “dead layers”. It is notably problematic in ferroelectric oxides, as their integration into nanoscale devices is obstructed by critical thickness for ferroelectricity as well as the associated uncontrolled domain formation [1,2]. In this work, we strive to provide solutions to these existing limitations with a non-conventional approach of epitaxially combining ferroelectric layers with different polar anisotropies. We identify the in-plane-polarized layered ferroelectrics of the Aurivillius phase as promising candidates for tuning interfacial electrostatics in hybrid heterostructures with ferroelectric perovskite oxides. Inserting an in-plane polarized Bi5FeTi3O15 Aurivillius epitaxial buffer [3] provides continuity of polarization at the interface, and despite its insulating nature, we observe the emergence of polarization in out-of-plane-polarized ferroelectric BaTiO3 from the very first unit cell. We additionally demonstrate that buffers of the Aurivillius phase can be instrumental for domain and domain-wall engineering in the room-temperature multiferroic BiFeO3. Remarkably, we observe homochiral polarization textures consistent with the recently proposed electric counterpart to the Dzyaloshinskii-Moriya interaction in magnetically ordered systems [4]. Our work thus suggests a new approach to oxide electronics going beyond the canonical perovskite systems and incorporating layered ferroelectrics for the stabilization of novel functional states.
[1] Junquera J and Ghosez P 2003 Critical thickness for ferroelectricity in perovskite ultrathin films Nature 422 506–9
[2] Strkalj N, De Luca G, Campanini M, Pal S, Schaab J, Gattinoni C, Spaldin N A, Rossell M D, Fiebig M and Trassin M 2019 Depolarizing-Field Effects in Epitaxial Capacitor Heterostructures Phys. Rev. Lett. 123 147601
[3] Gradauskaite E, Campanini M, Biswas B, Schneider C W, Fiebig M, Rossell M D and Trassin M 2020 Robust In-Plane Ferroelectricity in Ultrathin Epitaxial Aurivillius Films Adv. Mater. Interfaces 7 2000202
[4] Zhao H J, Chen P, Prosandeev S, Artyukhin S and Bellaiche L 2021 Dzyaloshinskii–Moriya-like interaction in ferroelectrics and antiferroelectrics Nat. Mater. 20 341–5


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