Vibronic mechanism of high-Tc superconductivity

Abstract

The dispersion of the in-plane Cu-O bond-stretching longitudinal optical phonon mode in the high-Tc superconducting cuprates shows strong softening with doping near the zone boundary. We suggest that it can be described with a negative electronic dielectric function that results in an overscreening of the intersite Coulomb interaction due to phonon-induced charge transfer and vibronic electron-phonon resonance. We propose that such a strong electron-phonon coupling of specific modes can form a basis for the phonon mechanism of high-temperature superconductivity. With the Eliashberg theory using the experimentally determined electron dispersion and dielectric function, we demonstrate the possibility of superconductivity with the order parameter of the dkx2−ky2 symmetry and the transition temperature well in excess of 100 K.

Source-reported materials — not catalogue approval

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