EVOLUTION OF THE ELECTRONIC RAMAN-SCATTERING OF HIGH-T-C SUPERCONDUCTORS WITH DOPING

For Bi2Sr2CaCu2O8+/-delta superconductors electronic Raman scattering from high-and low-energy excitations has been studied in relation to t he hole doping level, temperature and energy of the incident photons. For underdoped superconductors we conclude that: short range antiferro magnetic correlations persist with hole doping; the holes bind in loca l preformed pairs of B-1g symmetry and 600 cm(-1) binding energy; the pair concentration increases with temperature reduction until they gai n partial coherence and condense into a collective superconducting sta te.