Spectral signatures of critical charge and spin fluctuations in cuprates

TL;DR

This paper explores how Raman spectra reveal nearly-critical spin and charge fluctuations in cuprates, showing that Raman spectroscopy can distinguish their contributions and that these collective modes exhibit temperature-dependent masses and damping.

Contribution

It demonstrates the ability of Raman spectroscopy to identify and differentiate nearly-critical spin and charge collective modes in cuprates, highlighting their temperature-dependent properties.

Findings

Collective modes have temperature-dependent masses.

Spin modes are more diffusive and overdamped than charge modes.

Raman spectra can distinguish spin and charge contributions.

Abstract

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