Abstract
The phonons and the crystal structures of the -pyrochlore superconductors and are studied on single crystals by using micro-Raman spectroscopy. The symmetry of the modes is determined by polarization dependent measurements for various scattering geometries. It is concluded that the crystal structures are centrosymmetric . The vibrational frequencies have been computed from first principles and are in good agreement with the experimental data. The Raman-active rattling mode of the alkali ion is identified at 75 and for the K and Rb compounds, respectively.
- Received 14 January 2008
DOI:https://doi.org/10.1103/PhysRevB.77.134515
©2008 American Physical Society