High spatial resolution studies of phase transitions within organic aperiodic crystals

Céline Mariette (1) , Laurent Guérin (1) , Philippe Rabiller (1) , Christophe Odin (1) , Mariana Verezhak (1, 2) , Alexei Bosak (3) , Philippe Bourges (4) , Claude Ecolivet (1) , Bertrand Toudic (1)

1 IPR - Institut de Physique de Rennes
2 PSI - Paul Scherrer Institute
3 ESRF - European Synchrotron Radiation Facility
4 NFMQ - LLB - Nouvelles frontières dans les matériaux quantiques

The understanding of the symmetry breakings within crystals that are aperiodic by construction is actually very limited. Quasicrystals and incommensurate composite crystals may potentially allow such studies. We focus on the phase transitions of the aperiodic n-nonadecane/urea which recovers a translational symmetry within a four-dimensional space at room temperature. High-resolution neutron and synchrotron studies are reported as a function of the temperature on this organic crystal which presents an exceptional mosaicity. They reveal the richness of such approach, showing the appearance of very long wavelength supplementary intermodulations. This work generalizes the Landau theory to incommensurate composite crystals.

Domains: Physics [physics]

Céline Mariette, Laurent Guérin, Philippe Rabiller, Christophe Odin, Mariana Verezhak, et al.. High spatial resolution studies of phase transitions within organic aperiodic crystals. Physical Review B, 2020, 101 (18), ⟨10.1103/PhysRevB.101.184107⟩. ⟨hal-02634594⟩