Flattening of Single-Particle Spectra in Strongly Correlated Electron Systems and the Violation of the Wiedemann-Franz Law

TL;DR

This paper investigates how strong electron correlations lead to violations of the Wiedemann-Franz law, especially near quantum critical points and fermion condensation, supported by theoretical analysis and experimental comparisons.

Contribution

It demonstrates the violation of the Wiedemann-Franz law in strongly correlated systems due to spectrum flattening and diverging effective mass.

Findings

Wiedemann-Franz law is violated at quantum critical points.

Spectrum flattening correlates with WF law violation.

Experimental data supports theoretical predictions.

Abstract

The renormalization of the Wiedemann-Franz (WF) ratio in strongly correlated electron systems is analyzed within the Landau quasiparticle picture. We demonstrate that the WF law is violated: (i) at the quantum critical point, where the effective mass diverges, and (ii) beyond a point of fermion condensation, where the single-particle spectrum $\epsilon(p)$ becomes flat. Results of the analysis are compared with available experimental data.