Role of the electron-phonon interaction on the spectral density and pseudogap in cuprates

The pseudogap structure in low energy excitation in cuprates appears below a temperature and the spectral density exhibits strong wave-vector dependence. An electronic model that emphasized the coupling of carrier in Cu-O with phonon is examined for pseudogap. The electron-phonon interaction originates from the modulation of on-site and hopping energy and leads to spontaneous Jahn-Teller-like distortion and pseudogap below a critical temperature. At low temperature the spectral density has two-peak structure about the Fermi level for all k along Gamma-M whereas such structure exists along Gamma-X for small k only. The magnitude of pseudogap shows strong k-dependence maximum along Gamma-M and vanishes along Gamma-X. These features emphasize the role of electron-phonon interaction in formation of pseudogap.