Abstract

Bi 2Sr 2Ca 1−x(Y,Er,Tm) xCu 2O 8+δ single crystals have been investigated by Raman spectroscopy as a function of doping (0 ≤ x ≤ 0.85), incident laser wavelength, temperature and polarization directions of the incident and scattered light. Compared to undoped Bi 2Sr 2CaCu 2O 8+δ, additional phonons are found at 136 cm −1, 187 cm −1, 320 cm −1 and 434 cm −1. In contrast to superconducting samples, the B 1g -continuum of electronic scattering is not observed in semiconducting Bi 2Sr 2Ca 1−xY xCu 2O 8+δ (x ≥ 0.5), corroborating the identification of narrow (≈ 60 me V) band-like states near the Fermi energy in superconducting samples. Two-magnon scattering in non-superconducting Bi 2Sr 2Ca 1−x (Y,Er,Tm) xCu 2O 8+δ (x ≥ 0.5) gives rise to a broad peak with its maximum at ≈ 2900 cm −1, becoming more intense with increasing x.

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