Electrostatically Driven Polarization Flop and strain-induced Curvature in free-standing Ferroelectric Superlattices

TY - JOUR

T1 - Electrostatically Driven Polarization Flop and strain-induced Curvature in free-standing Ferroelectric Superlattices

AU - Li, Yaqi

AU - Zatterin, Edoardo

AU - Conroy, Michele

AU - Pylypets, Anastasiia

AU - Borodavka, Fedir

AU - Björling, Alexander

AU - Groenendijk, Dirk J.

AU - Lesne, Edouard

AU - Clancy, Adam J.

AU - Hadjimichael, Marios

AU - Kepaptsoglou, Demie

AU - Ramasse, Quentin

AU - Caviglia, Andrea

AU - Hlinka, Jiri

AU - Bangert, Ursel

AU - Leake, Steven

AU - Zubko, Pavlo

N1 - © 2022 The Authors.

PY - 2022/4/14

Y1 - 2022/4/14

N2 - Abstract The combination of strain and electrostatic engineering in epitaxial heterostructures of ferroelectric oxides offers many possibilities for inducing new phases, complex polar topologies, and enhanced electrical properties. However, the dominant effect of substrate clamping can also limit the electromechanical response and often leaves electrostatics to play a secondary role. Releasing the mechanical constraint imposed by the substrate can not only dramatically alter the balance between elastic and electrostatic forces, enabling them to compete on par with each other, but also activate new mechanical degrees of freedom, such as the macroscopic curvature of the heterostructure. In this work, an electrostatically driven transition from a predominantly out-of-plane polarized to an in-plane polarized state is observed when a PbTiO3/SrTiO3 superlattice with a SrRuO3 bottom electrode is released from its substrate. In turn, this polarization rotation modifies the lattice parameter mismatch between the superlattice and the thin SrRuO3 layer, causing the heterostructure to curl up into microtubes. Through a combination of synchrotron-based scanning X-ray diffraction imaging, Raman scattering, piezoresponse force microscopy and scanning transmission electron microscopy, the crystalline structure and domain patterns of the curved superlattices are investigated, revealing a strong anisotropy in the domain structure and a complex mechanism for strain accommodation. This article is protected by copyright. All rights reserved

AB - Abstract The combination of strain and electrostatic engineering in epitaxial heterostructures of ferroelectric oxides offers many possibilities for inducing new phases, complex polar topologies, and enhanced electrical properties. However, the dominant effect of substrate clamping can also limit the electromechanical response and often leaves electrostatics to play a secondary role. Releasing the mechanical constraint imposed by the substrate can not only dramatically alter the balance between elastic and electrostatic forces, enabling them to compete on par with each other, but also activate new mechanical degrees of freedom, such as the macroscopic curvature of the heterostructure. In this work, an electrostatically driven transition from a predominantly out-of-plane polarized to an in-plane polarized state is observed when a PbTiO3/SrTiO3 superlattice with a SrRuO3 bottom electrode is released from its substrate. In turn, this polarization rotation modifies the lattice parameter mismatch between the superlattice and the thin SrRuO3 layer, causing the heterostructure to curl up into microtubes. Through a combination of synchrotron-based scanning X-ray diffraction imaging, Raman scattering, piezoresponse force microscopy and scanning transmission electron microscopy, the crystalline structure and domain patterns of the curved superlattices are investigated, revealing a strong anisotropy in the domain structure and a complex mechanism for strain accommodation. This article is protected by copyright. All rights reserved

KW - ferroelectric domains

KW - free-standing membranes

KW - microtubes

KW - strain engineering

U2 - 10.1002/adma.202106826

DO - 10.1002/adma.202106826

M3 - Article

SN - 0935-9648

VL - 34

JO - Advanced Materials

JF - Advanced Materials

IS - 15

M1 - 2106826

ER -