When is the Kadowaki-Woods ratio universal?

TL;DR

This paper investigates the conditions under which the Kadowaki-Woods ratio (KWR) remains universal in multiband Fermi liquids, revealing its dependence on doping and band structure, contrary to previous assumptions of universality.

Contribution

The study derives the KWR for arbitrary band structures, identifies conditions for its universality, and extends the analysis to Dirac semimetals with considerations for dimensionality and doping effects.

Findings

KWR is not generally universal in multiband systems.

Universality is recovered in a specific limit of the model.

KWR depends strongly on doping and carrier density, especially in Dirac semimetals.

Abstract

We calculate the Kadowaki-Woods ratio (KWR) in Fermi liquids with arbitrary band structures. We find that, contrary to the single band case, the ratio is not generally independent of the effects of electronic correlations (universal). This is very surprising given the experimental findings of a near universal KWR in many multiband metals. We identify a limit where the universality of the ratio, which has been observed experimentally in many strongly correlated electron systems, is recovered. We discuss the KWR in Dirac semimetals in two and three dimensions. In the two-dimensional case we also generalize the KWR to account for the logarithmic factor in the self-energy. In both cases we find that the KWR is independent of correlations, but strongly dependent on the doping of the system: for massless fermions the KWR is proportional to the inverse square of the carrier density, whereas the KWR for systems with massive quasiparticles is proportional to the inverse of the carrier density.