TUNNELING SPECTROSCOPY IN BI2SR2CACU2O8-CRYSTAL BREAK JUNCTIONS - REPRODUCIBLE DETERMINATION OF THE ELIASHBERG FUNCTION AND ROLE OF THE BREAKDOWN OF MIGDALS THEOREM(X SINGLE)

We discuss the reproducible results in the determination of the electr on-phonon spectral function alpha(2)(omega)F(omega) we recently obtain ed from tunneling data in Bi2ST2CaCU2O8+x single-crystal break junctio ns with T-c = 93 K. The results give evidence for a strong electron-ph onon interaction (lambda = 2.94 +/- 0.34) possibly restricted to selec ted phonon modes. The role of the breakdown of Migdal's theorem is als o discussed by calculating the bare value of X and, try direct solutio n of the Eliashberg equations, the corresponding new values of T-c and Delta(0).