Light-scattering study of the superconducting energy gap in YBa/sub 2/Cu/sub 3/O/sub 7/ single crystals

Raman scattering experiments have been performed on single-crystal samples of YBa/sub 2/Cu/sub 3/O/sub 7/ in order to investigate superconducting gap excitations. The electronic contribution to the total scattering intensity can be fitted well by a theoretical model of light scattering from quasiparticle pairs. Depending on the measuring symmetry, mean gap energies are found ranging from 3.0 to 5.5 k/sub B/T/sub C/.