EFFECT OF NONADIABATICITY ON THE FERMI-EDGE PHOTOEMISSION AND TUNNELING SPECTRA OF SUPERCONDUCTORS

Temperature dependence of the experimental photoemission spectra of th e high-T-c superconductors have been interpreted and simulated by the recently formulated molecular nonadiabatic theory of the electron-vibr ational interaction. The change of the spectral feature below T-c' par ticularly formation of the narrow, near Fermi surface (FS) edge, peak separated by the dip from a broad spectral band at higher binding ener gies has been shown to be the consequence of the nonadiabatic electron -phonon coupling and corresponding properties of the nonadiabatic pola rons. 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.