Renormalization of the electron-phonon interaction by strong electronic correlations in high-{ital T}{sub {ital c}} superconductors

Journal Article · Thu Feb 01 04:00:00 EST 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.53.2850· OSTI ID:282790

Zeyher, R ^[1]; Kulic, M L ^[1]

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1. Max-Planck-Institut fuer Festkoerperforschung, 70569 Stuttgart (Germany)

The renormalization of the electron-phonon interaction by strong electronic correlations is studied using a one-band Hubbard model with infinite repulsion and nearest ({ital t} model) and nearest and second-nearest ({ital tt}` model) neighbor hopping terms and an on-site electron-phonon coupling. Using Hubbard`s {ital X} operators and an extension from 2 to {ital N} degrees of freedom for the electrons the leading contributions for the electron self-energy and the vertex function in 1/{ital N} and the electron-phonon coupling constant are given and numerically evaluated for a square lattice. We find that the momentum dependence of the vertex function depends strongly on doping: For large dopings it is rather weak, with decreasing doping it becomes more and more pronounced leading to a strong reduction of the vertex at larger momentum transfers until, for very small dopings, the vertex essentially consists of a forward scattering peak with a width proportional to the doping. This behavior occurs both in the {ital t} and the {ital tt}{prime} models and also in one dimension where analytic expressions are derived. Correlation effects also change {alpha}{sup 2}{ital F} in general: The full-symmetric component {alpha}{sup 2}{ital F}{sub 1} is in the {ital t} model somewhat, in the {ital tt}{prime} model rather strongly suppressed, especially near half-filling; the other symmetry components {alpha}{sup 2}{ital F}{sub {ital i}} with {ital i}=2,...,5 increase strongly with decreasing doping and are of similar magnitude as {alpha}{sup 2}{ital F}{sub 1} near half-filling. Including also direct Coulomb repulsion nontrivial symmetries such as {ital d} wave become more stable than the {ital s}-wave order parameter below a critical value for the doping even for the considered phonon-mediated superconductivity. Most dramatic is the quenching of the resistivity due to electron-phonon scattering both in the {ital t} and the {ital tt}` models at intermediate and small dopings.

• OSTI ID: 282790
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 5 Vol. 53; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
D WAVES
DOPED MATERIALS
ELECTRON-PHONON COUPLING
HIGH-TC SUPERCONDUCTORS
HUBBARD MODEL
NUMERICAL SOLUTION
RENORMALIZATION
S WAVES
SELF-ENERGY
VERTEX FUNCTIONS