Divergence of the Thermal Conductivity in Uniaxially Strained Graphene

TL;DR

This study reveals that uniaxial strain above 2% causes the thermal conductivity of graphene to diverge logarithmically, driven by changes in phonon behavior, which impacts thermal transport properties.

Contribution

It demonstrates that strain induces a divergence in graphene's thermal conductivity, providing insights into phonon dynamics under mechanical deformation.

Findings

Unstrained graphene has finite, size-convergent thermal conductivity.

Strained graphene's thermal conductivity diverges logarithmically with size.

Strain alters phonon populations and lifetimes, especially for low-frequency out-of-plane phonons.

Abstract

We investigate the effect of strain and isotopic disorder on thermal transport in suspended graphene by equilibrium molecular dynamics simulations. We show that the thermal conductivity of unstrained graphene, calculated from the fluctuations of the heat current at equilibrium is finite and converges with size at finite temperature. In contrast, the thermal conductivity of strained graphene diverges logarithmically with the size of the models, when strain exceeds a relatively large threshold value of 2%. An analysis of phonon populations and lifetimes explains the divergence of the thermal conductivity as a consequence of changes in the occupation of low-frequency out-of-plane phonons and an increase in their lifetimes due to strain.