Enhanced Thermoelectric Power in Graphene: Violation of the Mott Relation By Inelastic Scattering

TL;DR

This paper demonstrates that in ultra-clean graphene, strong inelastic scattering leads to thermoelectric power exceeding Mott relation predictions at high temperatures, revealing hydrodynamic behavior, but optical phonons limit this enhancement near room temperature.

Contribution

It provides experimental evidence and theoretical modeling of thermoelectric power enhancement in graphene due to inelastic scattering, highlighting a violation of the Mott relation.

Findings

TEP exceeds Mott relation at high temperature

Hydrodynamic limit approached due to inelastic scattering

Optical phonons suppress TEP near room temperature

Abstract

We report the enhancement of the thermoelectric power (TEP) in graphene with extremely low disorder. At high temperature we observe that the TEP is substantially larger than the prediction of the Mott relation, approaching to the hydrodynamic limit due to strong inelastic scattering among the charge carriers. However, closer to room temperature the inelastic carrier-optical-phonon scattering becomes more significant and limits the TEP below the hydrodynamic prediction. We support our observation by employing a Boltzmann theory incorporating disorder, electron interactions, and optical phonons.