Coupling to real and virtual phonons in tunneling spectroscopy of superconductors

TL;DR

This paper emphasizes the importance of including inelastic tunneling processes in the analysis of STM spectra of superconductors, which is essential for accurately identifying the pairing mechanism.

Contribution

It introduces a modified McMillan inversion algorithm that accounts for inelastic tunneling events in STM spectra analysis of superconductors.

Findings

Inelastic tunneling processes significantly affect STM spectral features.

Modified inversion algorithm improves identification of pairing interactions.

Application to Pb demonstrates the necessity of the new approach.

Abstract

Fine structures in the tunneling spectra of superconductors have been widely used to identify fingerprints of the interaction responsible for Cooper pairing. Here we show that for scanning tunneling microscopy (STM) of Pb, the inclusion of inelastic tunneling processes is crucial for the proper interpretation of these fine structures. For STM the usual McMillan inversion algorithm of tunneling spectra must therefore be modified to include inelastic tunneling events, an insight that is crucial for the identification of the pairing glue in conventional and unconventional superconductors alike.