Effect of nonadiabaticity on the fermi-edge photoemission and tunneling spectra of superconductors

Temperature dependence of the experimental photoemission spectra of the high-T-c superconductors have been interpreted and simulated by the recently formulated molecular nonadiabatic theory of the electron-vibrational interaction. The change of the spectral feature below T-c' particularly formation of the narrow, near Fermi surface (FS) edge, peak separated by the dip from a broad spectral band at higher binding energies has been shown to be the consequence of the nonadiabatic electron-phonon coupling and corresponding properties of the nonadiabatic polarons. Simulation yields very good fit to the experimental temperature-dependent spectra, with the calculated value of the gap 30.5 meV. (C) 1996 John Wiley & Sons, Inc.