ELECTRONIC RAMAN-SCATTERING OF OVERDOPED TL2BA2CUO6-FIELDS(DELTA IN HIGH MAGNETIC)

The excitations across the superconducting gap (2 Delta-peak in B-1g-s ymmetry Raman spectra) in an overdoped Tl2Ba2Cu6+delta single crystal have been studied as a function of temperature and held. The 2 Delta-p eak intensity, which we interpret as the density of the superconductin g condensate around the gap antinodes, is a linear function of tempera ture, but a nonlinear function of field. The latter is attributed to r enormalization of quasi-particle spectra in the vicinity of vortex lin es in the mixed state. The 2 Delta-peak is present above the irreversi bility line and yields a conventional temperature dependence of the ef fective upper critical field.