Raman scattering by a nested Fermi surface

Light coupling to energy fluctuations in a nonparabolic conduction band is found to yield a smooth Raman spectrum extending to an energy of 1 eV in the case of intermediate electron-electron scattering between nearly parallel ''nested'' sections of the Fermi surface. Nesting creates a frequency-dependent damping that produces a Raman line shape which exhibits a surprising proportionality to the optical conductivity. Evidence for the anomalous scattering is found in data on the high-temperature superconductor Bi2Sr2CaCu2O8 and in some rare-earth metals