Electron-phonon interaction in a strongly correlated Hubbard system

Saha Institute of Nuclear Physics, 92 Acharya Prafulla Chandra Road, Calcutta 700 009, India
Physica C Superconductivity (Impact Factor: 0.72). 01/1989; DOI: 10.1016/0921-4534(89)90343-2

ABSTRACT The electron-phonon (local) interactions have been considered in a single-band Hubbard model with strong on-site correlation. It has been shown that when no holes are present (i.e., one electron per site) the ground state of the system corresponds to the conventional coherent state of the phonon subsystem and the polaron has high effective mass, wheras for non-zero hole concentration the two-phonon coherent state of the phonon subsystem corresponds to the ground state of the system and the effective mass of the resulting squeezed polaron is reduced. If the superconductivity is due to Bose condensation of bipolarons the effective mass of the bisqueeps (squeezed bipolarons) at appropriate hole concentration may be reduced by 100 times or more in comparison to the conventional bipolarons and the corresponding Bose condensation temperature would be high.

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