Anomalous Optical Properties of KTN:Li Ferroelectric Supercrystals

Ludovica Falsi, Salvatore Macis, Yehonatan Gelkop, Luca Tartara, Eleonora Bonaventura, Paola Di Pietro, Andrea Perucchi, Yehudit Garcia, Galina Perepelitsa, Eugenio DelRe*, Aharon J. Agranat, Stefano Lupi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We report a spectroscopic investigation of potassium–lithium–tantalate–niobate (KTN:Li) across its room-temperature ferroelectric phase transition, when the sample manifests a supercrystal phase. Reflection and transmission results indicate an unexpected temperature-dependent enhancement of average index of refraction from 450 nm to 1100 nm, with no appreciable accompanying increase in absorption. Second-harmonic generation and phase-contrast imaging indicate that the enhancement is correlated to ferroelectric domains and highly localized at the supercrystal lattice sites. Implementing a two-component effective medium model, the response of each lattice site is found to be compatible with giant broadband refraction.

Original languageAmerican English
Article number899
Issue number5
StatePublished - 27 Feb 2023

Bibliographical note

Publisher Copyright:
© 2023 by the authors.


  • giant refraction
  • nanodisordered perovskite
  • nonlinear optics
  • spectroscopy
  • supercrystal


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