RAMAN CONTINUUM IN BILAYER CUPRATE SUPERCONDUCTORS

Experimentally the Raman continuum in the superconducting state of hig h T-c materials for the A(g) and B-g geometry of scattering exhibits p eaks far separated from each other (about 80 to 150 cm(-1)) in frequen cy. The former insensitive to doping variations over a small range nea r the optimal doping concentrations, where the T-c does not vary much, whereas the latter shifts towards higher frequencies for lesser hole concentrations. It is also observed that the peak position for the A(g ) continuum is very temperature sensitive, whereas the peak position o f the B-g geometry scattered intensity is only weakly dependent on tem perature. We calculate the electronic Raman scattering intensities usi ng the ''modified spin bag model'', and show that it offers a natural and quantitative explanation for the anomalous peak separation and the ir peculiar sensitivity to doping variations as well as to temperature . (C) 1997 Elsevier Science B.V.