We perform redundant x-ray diffraction versus temperature experiments in bulk transparent KTN. We find a violation of the standard perovskite cubic-to-tetragonal symmetry breaking at the Curie point in the form of an orthorhombic cell distortion. The lattice distortion spans coherently macroscopic volumes of the sample and is characterized by a negative-to-zero thermal volume expansion. Dielectric measurements and calorimetry indicate that the anomalous behavior is not associated to a distinct thermodynamic phase. The comparison of linear and nonlinear optical scattering experiments with structural data suggests that the lattice distortion is a consequence of strain relaxation to a 3D superlattice of polarization vortices.

Observation of an exotic lattice structure in the transparent KTa1-xNbx O3 perovskite supercrystal / L. Lo Presti, J. Parravicini, R. Soave, G. Parravicini, M. Mauri, L. Loconte, F. Di Mei, L. Falsi, L. Tartara, S. Binetti, A.J. Agranat, E. Delre. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 102:21(2020 Dec 17).

Observation of an exotic lattice structure in the transparent KTa1-xNbx O3 perovskite supercrystal

L. Lo Presti
Primo
Investigation
;
J. Parravicini
Secondo
Investigation
;
R. Soave
Formal Analysis
;
L. Loconte
Membro del Collaboration Group
;
2020

Abstract

We perform redundant x-ray diffraction versus temperature experiments in bulk transparent KTN. We find a violation of the standard perovskite cubic-to-tetragonal symmetry breaking at the Curie point in the form of an orthorhombic cell distortion. The lattice distortion spans coherently macroscopic volumes of the sample and is characterized by a negative-to-zero thermal volume expansion. Dielectric measurements and calorimetry indicate that the anomalous behavior is not associated to a distinct thermodynamic phase. The comparison of linear and nonlinear optical scattering experiments with structural data suggests that the lattice distortion is a consequence of strain relaxation to a 3D superlattice of polarization vortices.
perovskite; X-ray diffraction; nonlinear response; dielectric spectroscopy; hypervortex; supercrystal
Settore CHIM/02 - Chimica Fisica
Settore CHIM/03 - Chimica Generale e Inorganica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/822116
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