A Raman study of phonon mode softening in superconducting and non-superconducting (RE)Ba₂Cu₃O₇ for RE = Y,Eu,Pr

We have measured the mode frequency amd linewidth of the Ag(B1g) phonon mode which exhibits softening below the superconducting transition in the YBa2Cu3O7 (Y123) family of high temperature superconductors. Measurements were made on Y123, Eu123 and on non-superconducting Pr123. The mode softens by 10 cm-1 in Y123, by 3 cm-1 in Eu123 and shows no anomaly in Pr123. © 1989.