Behavior of the Raman continuum and Raman ‘‘gap’’ in ${\mathit{T}}_{\mathit{c}}$=60 K ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$

Numerous Raman investigations of the 90-K phase of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ have revealed broad features at approximately 350 and 500 ${\mathrm{cm}}^{\mathrm{-}1}$ in the ${\mathit{A}}_{1\mathit{g}}$ and ${\mathit{B}}_{1\mathit{g}}$ symmetries, respectively, which exhibit behavior qualitatively similar to the ‘‘gap’’ redistribution expected of a BCS-like superconductor. We find, however, that in decreasing the oxygen concentration to achieve an untwinned ${\mathit{T}}_{\mathit{c}}$=60 K single crystal the gaplike features do not exhibit straightforward BCS behavior. Rather, the 500-${\mathrm{cm}}^{\mathrm{-}1}$ ${\mathit{B}}_{1\mathit{g}}$ peak is found to be insen- sitive to the change in carrier concentration and is found to persist well into the normal state while the ${\mathit{A}}_{1\mathit{g}}$ peak exhibits significant broadening and no apparent softening. In addition, we present results on the room-temperature phonons and on an anomalous response of the background continuum to incident laser power.