Giant violation of Wiedemann-Franz law in doping layers of modern AlGaAs heterostructures

TL;DR

This paper analyzes recent experimental data on GaAs/AlGaAs heterostructures, revealing a significant violation of the Wiedemann-Franz law where thermal conductivity remains high despite low electrical conductivity, possibly due to exciton effects.

Contribution

It provides a detailed analysis of experimental data showing a violation of the Wiedemann-Franz law and suggests exciton contributions as a possible explanation.

Findings

Thermal conductivity is similar to metals despite low electrical conductivity.

Observation of Wiedemann-Franz law violation in doping layers.

Potential role of excitons in thermal transport.

Abstract

We analyze the data of the recent paper Nature 559, 205 (2018) and show that it contains an observation of thermal and electric conductivities of the doping layers in GaAs/AlGaAs heterostructures which violates the Wiedemann-Franz law. Namely, the measured thermal conductivity of the doping layers is similar to that of a metal while the electrical conductivity is exponentially small. We find that these results may be related to the exciton contribution to thermal conductivity calculated in several recent theoretical works for metallic samples.