Analysis of Phonon Structures in the Tunneling Conductance of Bi-Cuprates

Abstract

Following a short summary of our tunneling results for Bi₂Sr₂Ca_n−1Cu_nO_y (Bi22(n−1)n) (n=1–3), the tunneling phonon structures of Bi2212 are analyzed according to the Eliashberg scheme assuming a certain normal-state conductivity. The McMillan-Rowell spectral function is similar to a model spectral function in which only the Cu–O vibrations are taken into account and the interaction strength is assumed to increase with decreasing frequency. To ascertain whether excitation other than that of phonons contributes to pair formation, we calculated the tunneling conductance for various composite spectral functions. As far as we could discover, the phonon-only spectral function is the function which best explains the tunneling results.