Disentangling the electronic and phononic glue in a high-Tc superconductor

TL;DR

This study uses advanced optical spectroscopy to distinguish electronic and phononic contributions to the bosonic excitations in a high-Tc superconductor, revealing the electronic part's dominant role in achieving high critical temperature.

Contribution

It introduces a time- and frequency-resolved optical spectroscopy method to separate electronic and phononic contributions in a superconductor, clarifying their roles in high-temperature superconductivity.

Findings

Electronic excitations account for the high Tc.

The spectral distribution of electronic interactions explains the superconducting transition.

The electron-boson coupling strength is approximately 1.1.

Abstract

Unveiling the nature of the bosonic excitations that mediate the formation of Cooper pairs is a key issue for understanding unconventional superconductivity. A fundamen- tal step toward this goal would be to identify the relative weight of the electronic and phononic contributions to the overall frequency (\Omega) dependent bosonic function, \Pi(\Omega). We perform optical spectroscopy on Bi2212 crystals with simultaneous time- and frequency-resolution; this technique allows us to disentangle the electronic and phononic contributions by their different temporal evolution. The strength of the interaction ({\lambda}~1.1) with the electronic excitations and their spectral distribution fully account for the high critical temperature of the superconducting phase transition.