Universality of the single-particle spectra of cuprate superconductors

TL;DR

This paper demonstrates that the single-particle spectra of cuprate superconductors exhibit universal features across different doping levels and compounds, which are accurately explained by a recent microscopic theory.

Contribution

It shows that all available data on dispersion and linewidth in cuprates can be quantitatively fitted by a microscopic theory with nearly universal parameters.

Findings

Linearity of linewidth in energy below a certain scale

Constant linewidth above the scale

Universal fitting parameters across different cuprates and dopings

Abstract

All the available data for the dispersion and linewidth of the single-particle spectra above the superconducting gap and the pseudogap in metallic cuprates for any doping has universal features. The linewidth is linear in energy below a scale $\omega_c$ and constant above. The cusp in the linewidth at $\omega_c$ mandates, due to causality, a "waterfall", i.e., a vertical feature in the dispersion. These features are predicted by a recent microscopic theory. We find that all data can be quantitatively fitted by the theory with a coupling constant $\lambda_0$ and an upper cutoff at $\omega_c$ which vary by less than 50% among the different cuprates and for varying dopings. The microscopic theory also gives these values to within factors of O(2).