By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and onsite electron–electron interactions results in “intersite” or “onsite” two-electron (bipolaronic) solutions of the Holstein–Hubbard model, depending on the strengths of the interactions. On this basis, we argue that the decrease in the superconducting transition temperature of Bi-2212 compounds, following the enhancement of the electron–phonon interaction recently reported by Devereaux et al. [10] might be a consequence of the above mechanism, which leads to a transition from itinerant (intersite) to bound immobile (onsite) bipolarons, thus effectively reducing the number of superconducting carriers.
Bipolaron localization for increasing electron-phonon coupling in a small cluster
STRINATI CALVANESE, Giancarlo
2001-01-01
Abstract
By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and onsite electron–electron interactions results in “intersite” or “onsite” two-electron (bipolaronic) solutions of the Holstein–Hubbard model, depending on the strengths of the interactions. On this basis, we argue that the decrease in the superconducting transition temperature of Bi-2212 compounds, following the enhancement of the electron–phonon interaction recently reported by Devereaux et al. [10] might be a consequence of the above mechanism, which leads to a transition from itinerant (intersite) to bound immobile (onsite) bipolarons, thus effectively reducing the number of superconducting carriers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
