Influence of electron-phonon interaction on spin-fluctuation-induced superconductivity

T. S. Nunner; J. Schmalian; K. H. Bennemann

doi:10.1103/PhysRevB.59.8859

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Influence of electron-phonon interaction on spin-fluctuation-induced superconductivity

T. S. Nunner, J. Schmalian, K. H. Bennemann

DOI 10.1103/PhysRevB.59.8859 · Physical Review B

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Abstract

We investigate the interplay of the electron-phonon and the spin-fluctuation interaction in the superconducting state of YBa2Cu3O7. The spin fluctuations are described within the nearly antiferromagnetic Fermi-liquid theory and the phonons are treated using a shell-model calculation of all phonon branches. The electron-phonon coupling is calculated using rigidly displaced ionic potentials screened by a background dielectric constant ɛ∞ and by holes within the CuO2 planes. We get a superconducting state with dx2−y2 symmetry whose origin is antiferromagnetic spin fluctuations. The phononic contribution of all phonon modes of the system to the d-wave pairing interaction is attractive. This gives a positive isotope effect. The size of the isotope exponent depends strongly on the relative strength of the electron-phonon and spin-fluctuation coupling. Due to the strong electronic correlations no phononic induced superconducting state of s-wave character, is possible.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	110	Pressure not reported	onset
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	90	Pressure not reported	unknown