Soft-phonon driven hexagonal-orthorhombic phase transition in BaVS 3
Résumé
The lattice dynamics of low-dimensional BaVS3 is reported accross the hexagonal-orthorhombic phase transition occuring at TS = 250 K using a combination of Thermal Diffuse Scattering of X-rays, Inelastic X-ray Scattering and DFT calculations. We observed the occurence of strongly temperature-dependent diffuse scattering upon approaching the transition, centered at the Γ points associated with weak Bragg reflections with odd L. Inelastic scattering experiment related this observation to the condensation of a low-lying overdamped optical phonon at the Brillouin zone center, evidenced by significant variations of quasi-elastic scattering. These results unravel the dynamical origin of the zigzag distortion of the V chains at TS, which is probably a prerequisite of the Peierls anomaly driving the metal-insulator transition at T MI = 70 K.
Fichier principal
Girard et al. - 2019 - Soft-phonon driven hexagonal-orthorhombic phase tr.pdf (6.24 Mo)
Télécharger le fichier
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|
Loading...