Nonlocal electron-phonon coupling of ionic charge-fluctuation type and phonon anomalies in high-temperature superconductors

Claus Falter; Georg A. Hoffmann

doi:10.1103/PhysRevB.64.054516

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Nonlocal electron-phonon coupling of ionic charge-fluctuation type and phonon anomalies in high-temperature superconductors

Claus Falter, Georg A. Hoffmann

DOI 10.1103/PhysRevB.64.054516 · Physical Review B

T1

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Abstract

The experimentally observed strong renormalization of the high-frequency copper-in-plane-oxygen bond-stretching vibrations in the metallic phase of YBa2Cu3O7 and La2CuO4 is investigated. In this context the effect of the a−b anisotropy in YBa2Cu3O7 on these anomalous phonon modes is discussed. It is demonstrated that the characteristic softening of the modes is a generic feature of the high-temperature superconductors. It is a consequence of a strong, nonlocal electron-phonon coupling of the ionic charge-fluctuation type and not related to Fermi-surface nesting. The phase space of this strong coupling effect is shown to be large. This reveals the importance of the phonons in the mechanism leading to high-temperature superconductivity.

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.	—	Pressure not reported	unknown
La2CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown