ON ELECTRONIC RAMAN-SCATTERING FROM HIGH-TC LAYERED SUPERCONDUCTING MATERIALS

The nature of electronic Raman scattering from anisotropic layered high-Tc materials has been considered. Approximate expressions for the electronic Raman scattering from both charge-density fluctuations (CDF) and spin-density fluctuations (SDF) in these materials with nonparabolic energy bands and anisotropic Fermi surfaces have been derived. It is shown that in the normal state the unscreened part of the single-particle electronic Raman scattering has a width of about 2ωcn in the collision-dominated regime in which the normal state collision frequency ωcn≫q·vf, where h{stroke}q is the momentum transfer in the scattering process and vF is the Fermi velocity. Although, the normal state Raman spectrum is not as flat as observed experimentally, the possibility that most of the spectrum may be arising from such collision-dominated single-particle excitations, cannot be ruled out completely. More careful experimentation is required to confirm unambiguously the existence of any novel type of electronic excitations in the system. © 1990.