Impact of contact resistance in Lorenz number measurements

TL;DR

This paper investigates how contact resistance affects the accuracy of Lorenz number measurements in thermal transport experiments, emphasizing its impact on detecting violations of the Wiedemann-Franz law.

Contribution

It identifies the conditions under which contact resistance causes false negatives in Lorenz number measurements, highlighting the need for improved contact resistance in non-Fermi liquid studies.

Findings

Contact resistance can significantly underestimate the Lorenz number when it is enhanced.

The effect of contact resistance is less pronounced when the Lorenz number is suppressed.

Improving contact resistance is crucial for accurate thermal transport measurements.

Abstract

We analyze the effect of contact resistance on the Lorenz number measurement based on direct electronic thermal conductivity experiments. The contact resistance can significantly limit the experimental measured value when the Lorenz number is enhanced, but not as much so when it is suppressed, should the Wiedemann-Franz law be violated. The result provides the conditions of the potential false negative error and highlights the importance of improving the contact resistance in studying non-Fermi liquid behavior in thermal transport experiments.