Raman spectrum of the superconductor Bi2Sr2CaCu2O8

Abstract

Two Raman setups, one with high resolution, and the other for spatially resolved (1×1 μm2) experiments, have been used to investigate the polarized Raman spectra of a superconducting single crystal of the (2:2:1:2) phase Bi2Sr2CaCu2O8, and the unpolarized micro-Raman spectra of three ceramics, two of which have zero resistance below ∼105 K and contain substantial proportions of the (2:2:2:3) phase (∼15%-20%). Our spectra differ in some aspects from those recently published for the (2:2:1:2) phase. The occurrence of several low-frequency lines (ν≤65 cm−1) is confirmed. The width of the lines and their shape is discussed with regard to the occurrence of disorder in the structure and of an electron-phonon coupling. The spectra of the ceramics reveal the presence of four minority phases in addition to the main phases (2:2:1:2) and (2:2:2:3). The ceramics containing the (2:2:2:3) phase display the same lines as the ceramic not containing this phase. This result is discussed in the light of the structural information available and of the grain-growth habit of the (2:2:1:2) phase.

Source-reported materials — not catalogue approval

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