Transition from incoherent to coherent phonon thermal transport across graphene/h-BN van der Waals superlattices

Abstract

The van der Waals (vdW) superlattice, obtained by applying the concept of the periodic superlattice to two-dimensional materials using low-energy vdW physical assembly, is undoubtedly an instrumental avenue for the modulation of material properties. In the field of nanoscale thermal transport, the influence of the periodic structure of superlattice on the wave-particle phonon transport regime arouses substantial interests from the standpoint of basic physics and applied science. In the Graphene/h-BN vdW superlattice, we have found the wave-particle crossover of phonon transport, which is reflected in the transition from incoherent to coherent regime as the interface density increases. The analysis reveals that the increased thermal conductivity owing to coherent transport effects will amply compensate for the progressively increasing interface phonon scattering throughout this process. In addition, due to the stronger effects of the above two aspects, the superlattices with higher interface density are more sensitive to changes in temperature and interface coupling strength, which are manifested in the rate of change in thermal conductivity caused by their alteration, respectively. These results establish an in-depth understanding of coherent phonon transport while exploring the possibility of phonon wave-particle crossover in vdW superlattices, providing guidance for related thermal management based on phonon engineering.