Effect of antiferromagnetic spin fluctuations on the phonon-mediated pair interaction in high-T c superconductors

1573-7357

74.7e.−h ; 74.25. Kc ; 71.27.+a ; 63.20. Kr

Springer Online Journal Archives 1860-2000

Physics

Abstract We investigate the effect of electronic correlations on the phonon-mediated part of the pair interaction by including the effect of an exchange interaction U between the electrons in the calculation of the phonon frequencies and the electron-phonon vertices. We employ two RPA models: the first, consisting of a direct Coulomb interaction in addition to U, leads to softer phonons and an enhanced attractive s-wave phonon-induced electron-electron interaction while the second, a pure Hubbard model, yields the opposite effect. The weak-coupling selfconsistency equation for the order parameter in the 2D first Brillouin zone is solved for a tight-binding band. The change of Tc arises primarily from the change of the phonon frequencies rather than from the vertex renormalization.

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