Strong-coupling analysis of scanning tunneling spectra in Bi2Sr2Ca2Cu3O10 + y (Bi-2223)

Abstract

We study a series of spectra measured in the superconducting state of optimally-doped Bi-2223 by scanning-tunneling spectroscopy. Each spectrum, as well as the average of spectra presenting the same gap, is fit using a microscopic model that takes into account the band structure, the BCS gap, and the interaction of electrons with the spin-resonance mode. After describing our measurements and the main characteristics of the strong-coupling model, we report the whole set of parameters determined from the fits, and we discuss trends as a function of the gap magnitude. We also simulate angle-resolved photoemission spectra using the parameters resulting from our fits, and compare with recent experimental data.