Low-energy signatures of charge and spin fluctuations in Raman and optical spectra of the cuprates

TL;DR

This paper models fermion quasiparticles coupled to critical collective modes to identify how charge and spin fluctuations manifest in Raman and optical spectra of cuprates, revealing detectable signatures in Raman spectra despite optical masking.

Contribution

It introduces a phenomenological model highlighting how Raman spectra can reveal charge and spin fluctuation signatures in cuprates, overcoming optical spectrum limitations.

Findings

Critical signatures are detectable in Raman spectra due to symmetry properties.

Optical spectra may mask critical scaling due to charge conservation.

Comparison with experiments supports the model's relevance.

Abstract

We calculate the optical and Raman response within a phenomenological model of fermion quasiparticles coupled to nearly critical collective modes. We find that, whereas critical scaling properties might be masked in optical spectra due to charge conservation, distinct critical signatures of charge and spin fluctuations can be detected in Raman spectra exploiting specific symmetry properties. We compare our results with recent experiments on the cuprates.