Two-band model for high T_c superconductivity in La_2-x(Ba,Sr)_xCuO₄

For La27minus;x(Ba, Sr)xCuO4 systems, it is proposed that due to the electron-electron correlation, the copper dz2 (antibonding) band is lifted to the Fermi level and hence overlaps with the copper dx2-y2 (antibonding) band. Two possible mechanisms which could give rise to Tc enhancement are presented. They are a) the interband scattering mediated by phonons, and b) the additional attractive interaction between dx2-y2 electrons mediated by the dz2 hole-band plasmons and/or dx2-y2 ←→ dz2 interband transition. © 1987.