Interplay of superconductivity and bosonic coupling in the peak-dip-hump structure of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$

TL;DR

This study uses time-resolved ARPES to investigate the relationship between electron-boson coupling and superconductivity in cuprates, revealing that spectral weight shifts correlate with the destruction of superconductivity, thus providing insights into the pairing mechanism.

Contribution

It demonstrates a causal link between bosonic mode contributions and superconductivity in cuprates using time-resolved ARPES and theoretical simulations.

Findings

Spectral weight shifts into the dip as superconductivity is destroyed.

The magnitude of spectral weight shift depends on the bosonic mode’s contribution to pairing.

Results support a connection between electron-boson coupling and high-temperature superconductivity.

Abstract

Because of the important role of electron-boson interactions in conventional superconductivity, it has long been asked whether any similar mechanism is at play in high-temperature cuprate superconductors. Evidence for strong electron-boson coupling is observed in cuprates with angle-resolved photoemission spectroscopy (ARPES), in the form of a dispersion kink and peak-dip-hump structure. What is missing is evidence of a causal relation to superconductivity. Here we revisit the problem using the technique of time-resolved ARPES on Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. We focus on the peak-dip-hump structure, and show that laser pulses shift spectral weight into the dip as superconductivity is destroyed on picosecond time scales. We compare our results to simulations of Eliashberg theory in a superconductor with an Einstein boson, and find that the magnitude of the shift in spectral weight depends on the degree to which the bosonic mode contributes to superconductivity. Further study could address one of the longstanding mysteries of high-temperature superconductivity.