Anomalous dispersion of LO phonon branches in Ba0.6K0.4BiO3
Forschungszentrum Karlsruhe, INFP - Postfach 3640, 76021 Karlsruhe, Germany
2 Laboratoire Léon Brillouin (CEA-CNRS), CE-Saclay, 91191 Gif-sur-Yvette Cedex, France
3 Russian Research Center Kurchatov Institute - 123182 Moscow, Russia
Accepted: 4 April 1996
The high-frequency oxygen vibrations in superconducting have been studied by inelastic neutron scattering. The results give evidence that the Coulomb forces between the ions are screened only imperfectly. The highest LO branches associated with the Bi-O bond stretching vibrations exhibit an anomalous shape with a particularly pronounced frequency renormalization of the one-dimensional breathing mode. The dispersion resembles that of corresponding branches in the cuprate superconductors.
PACS: 74.70.-b – Superconducting materials (excluding high-Tc cuprates) / 74.25.Kc – Phonons / 63.20.Kr – Phonon-electron interactions
© EDP Sciences, 1996