Tunneling spectrum analysis regarding phonon contribution to high T-c Cooper pairing

Improved tunneling spectroscopy with point contact junction of [BSCCO (2212)/SeOx]/Au-tip provided us information of the quasi-particle that mediates the high T-c Cooper pairing. Fine structure in the tunneling conductance derivative spectrum d(2)I/dV(2) - V reflects the quasi particle coupling spectrum function alpha(2)(omega)F(omega), and really significant peaks have been observed ranging to 0.2 epsilon V. Their peak energy level eV(i) could be systematically assigned by eV(i) - Delta = n epsilon(0) + h omega(i)(ph) with n = 0, 1, 2. Here h omega i means each phonon mode energy, and the characteristic energy epsilon(0) = 72 meV was found to correspond to the breathing mode which is essentially Cu-O bond stretching node. This means that these characteristic phonons play a significant role on the high T-c superconductivity. Similar peak series had been also observed in the infra-red (IR) optical reflection spectrum R(omega) by Capizzi et al. The Cooper pairing characteristics are discussed from the comparison between both spectra of the tunneling and the IR.