Phonon Raman scattering from slightly overdoped Bi2Sr2CaCu2O8+d samples have been investigated under hydrostatic pressure up to 7.2 GPa. Although most observed phonons harden linearly with increasing pressure, the Alg-type Cu mode at 140 cm-1 exhibits a nonlinear hardening with an inflection point around 2 GPa, similar to the dependence of Tc versus pressure. We also find that the mode-specific Grüneisen parameters scale inversely with the corresponding vibrational frequencies, a trend similar to what is observed for molecular solids. The data are interpreted in terms of a nonuniform structural compressibility that results in a redistribution of charge carriers within the Bi2Sr2CaCu2O8+d unit cell.
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 1999|
ASJC Scopus subject areas
- Condensed Matter Physics