title: Super-crystals in composite ferroelectrics.
abstract: As atoms and molecules condense to form solids, a crystalline state can emerge with its highly ordered geometry and subnanometric lattice constant. In some physical systems, such as ferroelectric perovskites, a perfect crystalline structure forms even when the condensing substances are non-stoichiometric. The resulting solids have compositional disorder and complex macroscopic properties, such as giant susceptibilities and non-ergodicity. Here, we observe the spontaneous formation of a cubic structure in composite ferroelectric potassium-lithium-tantalate-niobate with micrometric lattice constant, 10(4) times larger than that of the underlying perovskite lattice. The 3D effect is observed in specifically designed samples in which the substitutional mixture varies periodically along one specific crystal axis. Laser propagation indicates a coherent polarization super-crystal that produces an optical X-ray diffractometry, an ordered mesoscopic state of matter with important implications for critical phenomena and applications in miniaturized 3D optical technologies.
authors.affiliation: Dipartimento di Fisica, Università di Roma 'La Sapienza', Rome 00185, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Pierangeli
authors.affiliation: Dipartimento di Fisica, Università di Roma 'La Sapienza', Rome 00185, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ferraro
authors.affiliation: Dipartimento di Fisica, Università di Roma 'La Sapienza', Rome 00185, Italy.|Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome 00161, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Di Mei
authors.affiliation: Dipartimento di Fisica, Università di Roma 'La Sapienza', Rome 00185, Italy.|Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome 00161, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Di Domenico
authors.affiliation: Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: C E M
authors.initials: CE
authors.lastname: de Oliveira
authors.affiliation: Department of Applied Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: A J
authors.initials: AJ
authors.lastname: Agranat
authors.affiliation: Dipartimento di Fisica, Università di Roma 'La Sapienza', Rome 00185, Italy.
authors.forename: E
authors.initials: E
authors.lastname: DelRe