We perform redundant X-ray diraction versus temperature experiments in bulk transparent KTN. We nd 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 volumeexpansion. 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.
Lo Presti, L., Parravicini, J., Soave, R., Parravicini, G., Mauri, M., Loconte, L., et al. (2020). Observation of an exotic lattice structure in the transparent KTa1-xNbx O3 perovskite supercrystal. PHYSICAL REVIEW. B, 102(21) [10.1103/PhysRevB.102.214110].
Observation of an exotic lattice structure in the transparent KTa1-xNbx O3 perovskite supercrystal
J. Parravicini
Secondo
;M. Mauri;S. Binetti;
2020
Abstract
We perform redundant X-ray diraction versus temperature experiments in bulk transparent KTN. We nd 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 volumeexpansion. 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.