Nonmonotonic phonon thermal conductivity modulated by electron–phonon interaction in graphene/h-BN heterostructures

Abstract

Graphene van der Waals (vdW) heterostructures, particularly those combined with hexagonal boron nitride (h-BN), exhibit unique electron–phonon interaction (EPI), enabling remarkable electron transport phenomena such as ultrahigh mobility, electron hydrodynamic flow, and superconductivity. Despite extensive studies on electron transport, the effect of EPI on phonon thermal transport in such heterostructures remains underexplored. In this Letter, we study the EPI-driven modulation of phonon thermal conductivity (kph) in the bilayer graphene/h-BN heterostructure via first-principles calculations. We find that kph varies nonmonotonically with carrier concentration due to the evolution of the Fermi surface near the Dirac point. The maximum reduction in kph compared to its intrinsic value reaches 41% at 300 K and 51% at 200 K, significantly exceeding the reduction reported for pristine graphene at a comparable carrier concentration. This significant reduction originates from the broken out-of-plane symmetry in the graphene/h-BN heterostructure, which enables direct flexural (ZA) phonon–electron coupling, and the strong EPI of in-plane shear (TA′) mode induced by the interlayer vdW interaction. A phonon branch-resolved analysis further shows that the relative contribution of ZA phonon–electrons scattering to the reduction in kph decreases from 68% to 25% with increasing carrier concentration, while the contributions from TA and TA′ phonon–electron scattering initially rise and eventually stabilize at around 30%. Our results provide insight into how EPI affects the thermal transport of graphene vdW heterostructures and offer guidance for thermal management in graphene-based nanodevices.