Reference : Archetypal Soft-Mode-Driven Antipolar Transition in Francisite Cu3Bi(SeO3)(2)O2Cl
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/10993/45518
Archetypal Soft-Mode-Driven Antipolar Transition in Francisite Cu3Bi(SeO3)(2)O2Cl
English
Milesi-Brault, Cosme [Luxembourg Inst Sci & Technol, Mat Res & Technol Dept, 41 Rue Brill, L-4422 Belvaux, Luxembourg.]
Toulouse, Constance mailto [University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)]
Constable, Evan [Vienna Univ Technol, Inst Solid State Phys, A-1040 Vienna, Austria.]
Aramberri, Hugo [Luxembourg Inst Sci & Technol, Mat Res & Technol Dept, 41 Rue Brill, L-4422 Belvaux, Luxembourg.]
Simonet, Virginie [Univ Grenoble Alpes, Inst Neel, CNRS, F-38000 Grenoble, France.]
de Brion, Sophie [Univ Grenoble Alpes, Inst Neel, CNRS, F-38000 Grenoble, France.]
Berger, Helmuth [Ecole Polytech Fed Lausanne, Lab Phys Complex Matter, CH-1015 Lausanne, Switzerland.]
Paolasini, Luigi [European Synchrotron Radiat Facil, BP 220, F-38043 Grenoble, France.]
Bosak, Alexei [European Synchrotron Radiat Facil, BP 220, F-38043 Grenoble, France.]
Iñiguez, Jorge mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) >]
Guennou, Mael mailto [University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)]
5-Mar-2020
PHYSICAL REVIEW LETTERS
Amer Physical Soc
124
9
097603-6
Yes (verified by ORBilu)
International
0031-9007
College Pk
[en] Model materials are precious test cases for elementary theories and provide building blocks for the understanding of more complex cases. Here, we describe the lattice dynamics of the structural phase transition in francisite Cu3Bi(SeO3)(2)O2Cl at 115 K and show that it provides a rare archetype of a transition driven by a soft antipolar phonon mode. In the high-symmetry phase at high temperatures, the soft mode is found at (0,0,0.5) at the Brillouin zone boundary and is measured by inelastic x-ray scattering and thermal diffuse scattering. In the low-symmetry phase, this soft-mode is folded back onto the center of the Brillouin zone as a result of the doubling of the unit cell, and appears as a fully symmetric mode that can be tracked by Raman spectroscopy. On both sides of the transition, the mode energy squared follows a linear behavior over a large temperature range. First-principles calculations reveal that, surprisingly, the flat phonon band calculated for the high-symmetry phase seems incompatible with the displacive character found experimentally. We discuss this unusual behavior in the context of an ideal Kittel model of an antiferroelectric transition.
Luxembourg National Research FundLuxembourg National Research Fund [C16/MS/11348912/BIAFET/Guennou, INTER/ANR/16/11562984/EXPAND/Kreisel]
http://hdl.handle.net/10993/45518
10.1103/PhysRevLett.124.097603
C. M.-B., C. T., H. A., J. I., and M. G. acknowledge financial support by the Luxembourg National Research Fund under Projects No. C16/MS/11348912/BIAFET/Guennou and No. INTER/ANR/16/11562984/EXPAND/Kreisel.
FnR ; FNR11348912 > Mael Guennou > BIAFET > BIsmuth-based AntiFErroelectrics as Tunable materials > 01/09/2017 > 31/08/2020 > 2016

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