TEMPERATURE AND DOPING DEPENDENCE OF THE BI-SR-CA-CU-O ELECTRONIC-STRUCTURE AND FLUCTUATION EFFECTS

Angle-resolved photoemission data from bulk Bi2Sr2CaCu2O8+delta show c hanges in the excitation gap and line shape versus both doping and tem perature. We employ two different quantitative analyses; one to search for a gap closing temperature T, and the other to further characteri ze its relation to the superconducting transition temperature T-c. We present observations of the sharp feature near crystal momentum k=(1,0 ) in superconducting spectra, and its temperature and doping dependenc e. This temperature dependence is analyzed together with the shift in the spectral weight's lowest binding energy (leading edge). Finally, w e find evidence for persistence of this sharp peak at temperatures sli ghtly above T-c.