ELECTRONIC RAMAN SCATTERING IN COPPER OXIDE SUPERCONDUCTORS

Theoretical and experimental aspects of electronic Raman scattering in high-Tc superconductors are reviewed. Theoretical expressions for the cross-section are derived and compared with data on various cuprate systems. The general goal is to obtain information about the symmetry of the superconducting order parameter. Experimental results are presented for Bi2Sr2CuO6, Bi2Sr2CaCu2O8 and Nd1.84Ce0.16CuO4. It is demonstrated that the class of hole-doped superconductors seems to be characterized by a strong gap anisotropy reminiscent of unconventional dx2-y2 pairing. Electron-doped superconductors, on the other hand, show a behaviour which is more compatible with a conventional only slightly anisotropic energy gap.