Abstract
Improved tunneling spectroscopy with point contact junction of [BSCCO (2212) / SiOx] / Au-tip provided us information of the quasi-particle that mediates the high Tc Cooper pairing. Fine structure in the tunneling conductance derivative spectrum d2I/dV2 — V reflects the quasi particle coupling spectrum function α2(ω)F(gw), and really significant peaks have been observed ranging to 0.2eV. Their peak energy level eVi could be systematically assigned by eVi − Δ = nɛ0 + hωi(ph) with n=0, 1, 2, Here hωi, means each phonon mode energy, and the characteristic energy ɛ0 = 72 meV was found to correspond to the breathing mode which is essentially Cu-O bond stretching mode. This means that these characteristic phonons play a significant role on the high Tc superconductivity. Similar peak series had been also observed in the infra-red (IR) optical reflection spectrum, R(ε) by Capizzi et al. The Cooper pairing characteristics are discussed from the comparison between both spectra of the tunneling and the IR.
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