Effect of substrate modes on thermal transport in supported graphene

TL;DR

This study uses molecular dynamics to show how substrate interactions influence thermal conductivity in supported graphene, revealing that tuning surface coupling can control heat flow.

Contribution

It uncovers the counterintuitive effect that stronger substrate coupling can increase graphene's thermal conductivity by modifying phonon dispersion.

Findings

Coupling to substrate reduces graphene's thermal conductivity by an order of magnitude.

Increasing substrate interaction strength enhances thermal conductivity.

Coupling to Rayleigh waves increases phonon group velocity.

Abstract

We examine thermal transport in graphene supported on SiO2 using molecular dynamics simulations. Coupling to the substrate reduces the thermal conductivity (TC) of supported graphene by an order of magnitude, due to damping of the flexural acoustic (ZA) phonons. However, increasing the strength of the graphene-substrate interaction enhances the TC of supported graphene, contrary to expectations. The enhancement is due to the coupling of graphene ZA modes to the substrate Rayleigh waves, which linearizes the dispersion and increases the group velocity of the hybridized modes. These findings suggest that the TC of two-dimensional supported graphene is tunable through surface interactions, providing a novel possibility for controlled energy flow in nanomaterials.