Dimensional crossover of thermal transport in few-layer graphene materials

TL;DR

This study experimentally investigates how the thermal conductivity of few-layer graphene decreases as the number of layers increases from 2 to 4, revealing the role of phonon interactions in dimensional crossover.

Contribution

The paper provides experimental evidence of thermal conductivity reduction in few-layer graphene and explains the underlying phonon coupling mechanisms during the 2D to 3D transition.

Findings

Thermal conductivity decreases from ~3000 W/mK to 1500 W/mK as layers increase from 2 to 4.

Cross-plane phonon coupling influences heat conduction in few-layer graphene.

Results enhance understanding of thermal transport in low-dimensional materials.

Abstract

Graphene, in addition to its unique electronic and optical properties, revealed unusually high thermal conductivity. The fact that thermal conductivity of large enough graphene sheets should be higher than that of basal planes of bulk graphite was predicted theoretically by Klemens. However, the exact mechanisms behind drastic alteration of material's intrinsic ability to conduct heat as its dimensionality changes from 2-D to 3-D remain elusive. Recent availability of high-quality few-layer graphene materials allowed us to study dimensional crossover experimentally. Here we show that the room-temperature thermal conductivity changes from K~3000 W/mK to 1500 W/mK as the number of atomic plains in few-layer graphene increases from 2 to 4. We explained the observed evolution from 2-D to bulk by the cross-plane coupling of the low-energy phonons and corresponding changes in the phonon Umklapp scattering. The obtained results shed light on heat conduction in low-dimensional materials and may open up few-layer graphene applications in thermal management of nanoelectronics.