Two component dynamics of the superconducting order parameter revealed by time-resolved Raman scattering

TL;DR

This study uses time-resolved Raman scattering to reveal two distinct dynamical components of the superconducting order parameter in a high-$T_c$ cuprate, highlighting different coupling mechanisms and their relaxation behaviors.

Contribution

It introduces a novel pump-probe Raman technique to dissect the dual-component dynamics of the superconducting order parameter in cuprates, emphasizing the roles of phonons and hole-spin interactions.

Findings

Two coupling mechanisms contribute equally to the pair breaking peak.

One mechanism acts rapidly at 2ps and relaxes slowly.

The other mechanism is delayed at 5ps and relaxes quickly.

Abstract

We study the dynamics of the superconducting order parameter in the high-$T_c$ cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8-\delta}$ by employing a novel time-resolved pump-probe Raman experiment. We find two different coupling mechanisms that contribute equally to the pair breaking peak. One coupling sets in very fast at 2ps and relaxes slow, while the other one is delayed and sets in roughly at 5ps and relaxes fast. A model that couples holes through phonons is able to reproduce one part of the condensate dynamics, thus, we argue that hole-spin interactions are of importance as well.