Abstract
Lattice constants, resistivity, and Raman scattering spectra have been investigated for where is a trivalent rare-earth ion, with systematically changing the averaged ionic radius of the rare-earth ion. For Eu, Sm, prominent metal-insulator (MI) transition is observed at but the transition is suppressed for The MI transition becomes also blurred for suggesting that the transition is due to charge ordering. We have observed enhancement of intensity of Raman scattering from the Co-O stretching mode in the insulating state and have interpreted it in terms of folding of the oxygen phonon branch due to doubling of the cell size.
- Received 30 July 1998
DOI:https://doi.org/10.1103/PhysRevB.58.R13334
©1998 American Physical Society