Electronic Origin of the Inhomogeneous Pairing Interaction in the High-Tc Superconductor Bi2Sr2CaCu2O8+d

TL;DR

This study uses local spectroscopy to investigate the pairing mechanism in high-Tc cuprate superconductors, revealing that electron-electron interactions in the normal state drive superconductivity rather than low-energy bosonic couplings.

Contribution

It provides direct local measurements linking the pairing strength to electronic excitations, highlighting the role of strong electron-electron interactions in high-Tc superconductivity.

Findings

Pairing strength correlates with unusual electronic excitations in the normal state.

Electron-electron interactions, not low-energy bosonic modes, likely drive superconductivity.

Normal state electronic excitations influence the onset of pairing.

Abstract

Identifying the mechanism of superconductivity in the high-temperature cuprate superconductors is one of the major outstanding problems in physics. We report local measurements of the onset of superconducting pairing in the high-transition temperature (Tc) superconductor Bi2Sr2CaCu2O8+d using a lattice-tracking spectroscopy technique with a scanning tunneling microscope. We can determine the temperature dependence of the pairing energy gaps, the electronic excitations in the absence of pairing, and the effect of the local coupling of electrons to bosonic excitations. Our measurements reveal that the strength of pairing is determined by the unusual electronic excitations of the normal state, suggesting that strong electron-electron interactions rather than low-energy (<0.1 volts) electron-boson interactions are responsible for superconductivity in the cuprates.