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

Leonardo Lo Presti, Jacopo Parravicini*, Raffaella Soave, Gianbattista Parravicini, Michele Mauri, Laura Loconte, Fabrizio Di Mei, Ludovica Falsi, Luca Tartara, Simona Binetti, Aharon J. Agranat, Eugenio Delre

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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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.

Original languageAmerican English
Article number214110
JournalPhysical Review B
Issue number21
StatePublished - 17 Dec 2020

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