Induced superconductivity in noncuprate layers of the Bi2Sr2CaCu2O8+δ high-temperature superconductor: Modeling of scanning tunneling spectra
Abstract
We analyze how the coherence peaks observed in Scanning Tunneling Spectroscopy (STS) of cuprate high temperature superconductors are transferred from the cuprate layer to the oxide layers adjacent to the STS microscope tip. For this purpose, we have carried out a realistic multiband calculation for the superconducting state of Bi2Sr2CaCu2O8+δ (Bi2212) assuming a short range d-wave pairing interaction confined to the nearest-neighbor Cu dx2-y2 orbitals. The resulting anomalous matrix elements of the Green's function allow us to monitor how pairing is then induced not only within the cuprate bilayer but also within and across other layers and sites. The symmetry properties of the various anomalous matrix elements and the related selection rules are delineated.