Self-energy effects of the B1g phonon in Bi2Sr2CaCu2O8

Abstract Raman scattering in a Bi 2 Sr 2 CaCu 2 O 8 single crystal has been measured as a function of temperature. We report an anomalous decrease in linewidth of the B 1 g phonon (measured at 285 cm -1 ) near T c which we conclude is superconductivity related. We detect no frequency anomaly for this phonon. The decrease in linewidth indicates that the superconducting energy gap, or pseudogap, lies above 285 cm -1 .