Two Distinct Electronic Contributions in the Fully Symmetric Raman Response of High $T_{c}$ Cuprates

TL;DR

This paper identifies two separate electronic contributions in the fully symmetric Raman response of high-temperature cuprates, linking the pair-breaking peak and a collective mode to specific features in the spectrum.

Contribution

It demonstrates the presence of two distinct electronic contributions in the A₁g Raman response of high T_c cuprates, reconciling experimental observations with the d-wave model.

Findings

A₁g response includes a superconducting pair breaking peak and a collective mode.

The collective mode is close to the magnetic resonance energy.

Results support the existence of a collective mode separate from the pair breaking peak.

Abstract

We show by non resonant effect in HgBa$_2$CuO$_{4+\delta}$ (Hg-1201)and by Zn substitutions in YBa$_2$Cu$_3$O$_{7-\delta}$ (Y-123) compounds that the fully symmetric Raman spectrum has two distinct electronic contributions. The A$_{1g}$ response consists in the superconducting pair breaking peak at the 2$\Delta $ energy and a collective mode close to the magnetic resonance energy. These experimental results reconcile the \textit{d-wave} model to the A$_{1g}$ Raman response function in so far as a collective mode that is distinct from the pair breaking peak is present in the A$_{1g}$ channel.