Tunneling spectra of strongly coupled superconductors: Role of dimensionality

TL;DR

This paper numerically analyzes how the low dimensionality of layered high-Tc superconductors enhances collective mode signatures in tunneling spectra, revealing distinct features in d-wave versus s-wave superconductors and questioning existing models.

Contribution

It demonstrates that low dimensionality amplifies collective mode signatures and clarifies the differences in tunneling spectra between d-wave and s-wave superconductors.

Findings

Low dimensionality explains stronger signatures in high-Tc superconductors.

D-wave superconductors show dips in tunneling spectra, unlike steps in s-wave.

Effective density of states models may be inadequate for d-wave analysis.

Abstract

We investigate numerically the signatures of collective modes in the tunneling spectra of superconductors. The larger strength of the signatures observed in the high-Tc superconductors, as compared to classical low-Tc materials, is explained by the low dimensionality of these layered compounds. We also show that the strong-coupling structures are dips (zeros in the d2I/dV2 spectrum) in d-wave superconductors, rather than the steps (peaks in d2I/dV2) observed in classical s-wave superconductors. Finally we question the usefulness of effective density of states models for the analysis of tunneling data in d-wave superconductors.