Low-temperature thermal conductivity in polycrystalline graphene

TL;DR

This paper provides a theoretical analysis of low-temperature thermal conductivity in polycrystalline graphene, focusing on phonon scattering mechanisms and their impact on temperature dependence, especially in nanosized grain boundaries.

Contribution

It introduces a theoretical model accounting for border, defect, and grain boundary scattering, revealing how these affect thermal conductivity's temperature dependence in polycrystalline graphene.

Findings

Thermal conductivity exhibits a $T^{eta}$-behavior with $eta$ between 1 and 2.

Nanosized grain boundaries significantly enhance phonon scattering effects.

The model explains the variation in thermal conductivity with grain size and defect density.

Abstract

The low-temperature thermal conductivity in polycrystalline graphene is theoretically studied. The contributions from three branches of acoustic phonons are calculated by taking into account scattering on sample borders, point defects and grain boundaries. Phonon scattering due to sample borders and grain boundaries is shown to result in a $T^{\alpha}$-behaviour in the thermal conductivity where $\alpha$ varies between 1 and 2. This behaviour is found to be more pronounced for nanosized grain boundaries. PACS: 65.80.Ck, 81.05.ue, 73.43.Cd