Raman scattering from high-Tcsuperconductors

Abstract

Raman scattering experiments from high-$T_c$ superconductors of the R${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{d}}$ type, with R=Y, Pr, Nd, Eu, Gd, Dy, and Yb, are reported. Because of the great difficulty in obtaining single-phase samples, spectra from all starting compounds and other known phases of Y-Ba-Cu are presented. This systematic approach has allowed the identification of the lines observed in Raman spectra of the superconducting compounds as well as those of impurity phases. The lines originating from the superconducting yttrium compound were investigated as a function of quench temperature, and oxygen deficiency. Polarization studies on single crystals are also presented.