Phonon thermal transport in graphene/h-BN superlattice monolayers

The superlattice monolayers composed of periodically assembled graphene and hexagonal boron nitride (h-BN) superlattices by strong covalent bonds have aroused great interest in academia and industry due to their adjustable physical properties, which are expected to play an important role in the modulation of material properties, especially in thermal transport properties. In general, thermal transport properties highly rely on the characteristic of nanostructures. Thus, understanding the impact of structural characteristics on physical properties is essential for the design of high-performance materials. In this study, we report our results from three different methods including non-equilibrium molecular dynamics, homogeneous non-equilibrium molecular dynamics, and spectral heat current decomposition to explore the phonon thermal transport properties in different graphene/h-BN superlattice monolayers, which are constructed by periodically stitched and equal-sized graphene and h-BN superlattices. We find that the thermal conductivities decrease first and then increase with the increase of periodic length, corresponding to a transition from coherent transport to incoherent transport, and a minimum thermal conductivity at a certain period is identified. These results provide a theoretical validation of a possible control on thermal properties at the nanoscale, which may have potential applications in thermoelectric devices once upon experimental validation.