On the contribution of nearly-critical spin and charge collective modes to the Raman spectra of high-Tc cuprates

TL;DR

This paper investigates how nearly-critical spin and charge collective modes influence Raman spectra in high-Tc cuprates, revealing distinct signatures and temperature-dependent behaviors that help differentiate their contributions.

Contribution

It demonstrates that Raman spectra can detect nearly-critical collective modes and distinguishes spin from charge contributions using momentum space selectivity.

Findings

Collective modes show temperature-dependent masses consistent with near-criticality.

Spin modes are more diffusive and overdamped compared to charge modes.

Raman spectra exhibit specific fingerprints of collective modes near a stripe quantum critical point.

Abstract

We discuss how Raman spectra are affected by nearly-critical spin and charge collective modes, which are coupled to charge carriers near a stripe quantum critical point. We show that specific fingerprints of nearly-critical collective modes can indeed be observed in Raman spectra and that the selectivity of Raman spectroscopy in momentum space may also be exploited to distinguish the spin and charge contribution. We apply our results to discuss the spectra of high-Tc superconducting cuprates finding that the collective modes should have masses with substantial temperature dependence in agreement with their nearly critical character. Moreover spin modes should be more diffusive than charge modes indicating that in stripes the charge is nearly ordered, while spin modes are strongly overdamped and fluctuate with high frequency.