RESONANCE RAMAN-STUDY OF THE SUPERCONDUCTING GAP AND LOW-ENERGY EXCITATIONS IN TL2BA2CUO6+DELTA SUPERCONDUCTORS

Low energy electronic Raman scattering from Tl2Ba2CuO6+delta Single cr ystals with T-c = 25 and 85 K has been studied using excitation energi es from 1.65 to 3.05 eV. The B-1g 2 Delta peak position shows that the 2 Delta/k(B)T(c) value decreases as the doping level increases. The r esonance profiles of the 2 Delta peak and the continuum show similar a nd strong resonances towards the 3.4 eV optical absorption peak in bot h crystals, which indicates that (1) the 2 Delta peak and the continuu m are coupled to light scattering by the same mechanism, and (2) the l ight scattering mechanism for both features involves the 3.4 eV optica l absorption process.