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

We have analyzed the B1g and B2g Raman spectra of electron-doped cuprate superconductors Nd2-x Cex CuO4 and Pr2-x Cex CuO4 using a weakly coupled two-band model. One of these two bands is centered around (±π2, ±π2) and couples more strongly with the B2g mode, while the other is centered around (±π,0) and (0,±π) and couples more strongly with the B1g mode. This model explains in a natural way why the B2g Raman peak occurs at a higher frequency than the B1g 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 x2 - y2 -wave superconductivity is driven by the holelike band and a proximity effect on the electronlike band.