Two-band model of Raman scattering on electron-doped high-Tc superconductors

We have analyzed the B-1g and B-2g Raman spectra of electron-doped cuprate superconductors Nd2-xCexCuO4 and Pr2-xCexCuO4 using a weakly coupled two-band model. One of these two bands is centered around (+/-pi/2,+/-pi/2) and couples more strongly with the B-2g mode, while the other is centered around (+/-pi,0) and (0,+/-pi) and couples more strongly with the B-1g mode. This model explains in a natural way why the B-2g Raman peak occurs at a higher frequency than the B-1g one at optimal doping, and how these two peaks change with doping in agreement with experiments. The result thus supports that there are two kinds of quasiparticles in electron-doped cuprates and d(x)(2)-y(2)-wave superconductivity is driven by the holelike band and a proximity effect on the electronlike band.