Vertex functions as a factor of enhancing electron-electron attraction in d-wave channel of the "Coulomb" superconductivity mechanism

It is shown that many-particle Coulomb correlations described by Coulomb ve rtex functions Gamma (c) in layered high-T-c superconducting metal oxide cu prates substantially enhance effective electron-electron attraction in the d-wave Cooper-pairing channel. This attraction is due to the combined actio n of a strong in-layer anisotropy of the quasi-two-dimensional electronic s pectrum and the suppression of a screened Coulomb repulsion for small trans ferred momenta in small-angle charge-carrier scattering from long-wavelengt h charge-density fluctuations. Such a "Coulomb" mechanism of anisotropic Co oper pairing may provide high superconducting transition critical temperatu res (T-c greater than or equal to 100 K) for optimum-doped cuprates. (C) 20 00 MAIK "Nauka/ Interperiodica".