Pseudogap in electronic Raman spectra of Bi2Sr2CaCu2O8+delta

The Raman B-2g spectrum of underdoped Bi2212 (T-c=84K) is suppressed at ome ga less than or similar to 500cm(-1) (omega*) below similar to 175K (T*), m eaning the opening of a pseudogap below T*. On the other hand, no clear pse udogap behavior appears in the B-2g spectra of overdoped sample (T-c=82K). At T much less thanT(c), the B-2g spectra of both under- and overdoped samp les with almost the same T-c exhibit coherence peaks at almost the same fre quency similar to 450 cm(-1). This implies that T-c correlates with the ene rgy gap 2 Delta (c) determined from the B-2g spectra.