RAMAN-SCATTERING IN BI2SR2CA1-X(Y,ER,TM)XCU2O8+DELTA SINGLE-CRYSTALS

Bi2Sr2Ca1-x(Y,Er,Tm)xCu2O8+delta single crystals have been investigated by Raman spectroscopy as a function of doping (0 less-than-or-equal-to x less-than-or-equal-to 0.85), incident laser wavelength, temperature and polarization directions of the incident and scattered light. Compared to undoped Bi2Sr2CaCu2O8+delta, additional phonons are found at 136 cm-1, 187 cm-1, 320 cm-1 and 434 cm-1. In contrast to superconducting samples, the B1g-continuum of electronic scattering is not observed in semiconducting Bi2Sr2Ca1-xYxCu2O8+delta (x greater-than-or-equal-to 0.5), corroborating the identification of narrow (almost-equal-to 60 meV) band-like states near the Fermi energy in superconducting samples. Two-magnon scattering in non-superconducting Bi2Sr2Ca1-x(Y,Er,Tm)xCu2O8+delta (x greater-than-or-equal-to 0.5) gives rise to a broad peak with its maximum at almost-equal-to 2900 cm-1, becoming more intense with increasing x.