Apparent Violation of the Wiedemann-Franz law near a magnetic field tuned metal-antiferromagnetic quantum critical point

TL;DR

This paper models the temperature dependence of electrical and thermal resistivity near a magnetic quantum critical point, showing apparent violations of the Wiedemann-Franz law that are recovered at low temperatures, aligning with recent CeCoIn$_5$ experiments.

Contribution

It provides a theoretical explanation for the apparent violation of the Wiedemann-Franz law near a magnetic quantum critical point, reconciling experimental observations with Fermi liquid theory.

Findings

Resistivities show linear temperature dependence over broad ranges.

Extrapolations suggest violations of the Wiedemann-Franz law.

Law is recovered at low temperatures close to the critical point.

Abstract

The temperature dependence of the interlayer electrical and thermal resistivity in a layered metal are calculated for Fermi liquid quasiparticles which are scattered inelastically by two-dimensional antiferromagnetic spin fluctuations. Both resistivities have a linear temperature dependence over a broad temperature range. Extrapolations to zero temperature made from this linear-$T$ range give values that appear to violate the Wiedemann-Franz law. However, below a low-temperature scale, which becomes small close to the critical point, a recovery of this law occurs. Our results describe recent measurements on CeCoIn$_5$ near a magnetic field-induced quantum phase transition. Hence, the experiments do not necessarily imply a non-Fermi liquid ground state.