Preeminent role of the Van Hove singularity in the strong-coupling analysis of scanning tunneling spectroscopy for two-dimensional cuprates

TL;DR

This paper demonstrates that the Van Hove singularity significantly influences the interpretation of tunneling spectra in high-temperature cuprate superconductors, necessitating a revised strong-coupling analysis for accurate understanding.

Contribution

It introduces a microscopic model highlighting the critical role of the Van Hove singularity in shaping tunneling spectra, correcting previous analysis methods.

Findings

The Van Hove singularity causes electron-hole asymmetry in 2D density of states.

Conventional strong-coupling analyses can lead to errors without considering the VHS.

The proposed model accurately reproduces experimental tunneling spectra.

Abstract

In two dimensions the non-interacting density of states displays a Van Hove singularity (VHS) which introduces an intrinsic electron-hole asymmetry, absent in three dimensions. We show that due to this VHS the strong-coupling analysis of tunneling spectra in high-$T_c$ superconductors must be reconsidered. Based on a microscopic model which reproduces the experimental data with great accuracy, we elucidate the peculiar role played by the VHS in shaping the tunneling spectra, and show that more conventional analyses of strong-coupling effects can lead to severe errors.