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 M.
AU - Caviglia, Andrea D.
AU - Hlinka, Jiri
AU - Bangert, Ursel
AU - Leake, Steven J.
AU - Zubko, Pavlo
N1 - Publisher Copyright:
© 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.
PY - 2022/4/14
Y1 - 2022/4/14
N2 - 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 activates 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.
AB - 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 activates 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.
KW - ferroelectric domains
KW - free-standing membranes
KW - microtubes
KW - strain engineering
UR - http://www.scopus.com/inward/record.url?scp=85125487295&partnerID=8YFLogxK
U2 - 10.1002/adma.202106826
DO - 10.1002/adma.202106826
M3 - Article
AN - SCOPUS:85125487295
SN - 0935-9648
VL - 34
JO - Advanced Materials
JF - Advanced Materials
IS - 15
M1 - 2106826
ER -