Evidence of strong correlations at the van Hove singularity in the scanning tunneling spectra of superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} single crystals

TL;DR

This study uses advanced multiband calculations to analyze scanning tunneling spectra of Bi2212 superconductors, revealing strong correlations and a potential quantum critical point related to the Van Hove singularity.

Contribution

It introduces a realistic multiband modeling approach that includes effects of pseudogap, pairing gap, and strong correlations to interpret experimental spectra.

Findings

Good agreement with experimental two-gap features

Evolution of Van Hove singularity with doping

Possible quantum critical point near VHS crossing Fermi level

Abstract

We present realistic multiband calculations of scanning tunneling spectra in Bi_{2}Sr_{2}CaCu_{2} O_{8+\delta} over a wide doping range. Our modeling incorporates effects of a competing pseudogap and pairing gap as well as effects of strong electronic correlations, which are included by introducing self-energy corrections in the one-particle propagators. The calculations provide a good description of the two-gap features seen in experiments at low energies and the evolution of the Van Hove singularity (VHS) with doping, and suggest a possible quantum critical point near the point where the VHS crosses the Fermi level.