On the role of the Coulomb interaction in the mechanism of d-wave Cooper pairing of charge carriers in high-T-c superconductors

The question of the effect of the structure of the anisotropic quasi-two-di mensional electron spectrum of high-T-c superconductors on the character of the screening of the Coulomb interaction and the symmetry of the supercond ucting order parameter is studied. Calculations of the polarization operato r of electrons are performed on the basis of the single-particle band spect rum extracted from angle-resolved photoemission spectroscopy data. It is sh own that the static screened Coulomb repulsion has a minimum at small momen tum transfers. This corresponds to an effective electron-electron attractio n in the d(x2-y2)-wave channel of Cooper pairing of the charge carriers on account of their interaction with the long-wavelength charge-density fluctu ations. This attraction together with the anisotropic electron-phonon inter action increase the critical superconducting transition temperature T-c wit h increasing hole density and can give quite high values of T-c while at th e same time suppressing the isotope effect, in qualitative agreement with t he experimental data for underdoped hole-type cuprate metal-oxide compounds . (C) 1999 American Institute of Physics. [S0021-3640(99)00710-0].