RAMAN-SCATTERING IN A T-J MODEL - SLAVE-BOSON LARGE-N TECHNIQUE

We studied the electronic Raman scattering in a t-J model using the slave boson and large-N expansion to the next-to-leading order in 1/N. We found that a broad Raman continuum up to approximately 1 eV arises due to the incoherent motion of charge carriers, which is also the origin of the anomalous absorption power ranging from mid-infrared to higher frequency in optical conductivity, as recently shown by Bang and Kotliar. This unified resolution for both anomalies within the microscopic model of strongly correlated electrons reinforces the viewpoint that the essential physics of high-T(c) cuprates lies in the Mott-Hubbard system. The intensity of the Raman scattering as a function of doping shows a non-trivial behavior in contrast to the optical conductivity. We also discuss the implications of our results for the ''marginal Fermi liquid (MFL)'' theory.