Thermal transport in periodic and quasiperiodic graphene-hBN superlattice ribbons

Abstract

Abstract Nanostructured superlattices are expected to play a significant role in the next generation of technological devices, specially due to their adjustable physical properties. In terms of heat transport, materials with low thermal conductivities can be useful in thermoelectric devices or heat shields, while materials with high thermal conductivities are fundamental for heat dissipation in miniaturized electronic devices. In general, transport properties are dominated by translational symmetry and the presence of unconventional symmetries might lead to unusual transport characteristics. In this work, we report our results from nonequilibrium molecular dynamics simulations to investigate phonon heat transport in periodic and quasiperiodic graphene-hBN superlattices. The periodic superlattices are built with alternating equal-sized domains of graphene and hBN, while the quasiperiodic case follows the Fibonacci sequence, which lies between periodic and disordered structures. Periodic superlattices can facilitate coherent phonon transport due to constructive interference at the boundaries between the materials. Nonetheless, it is possible to induce a crossover from a coherent to an incoherent transport regime by increasing the length of individual domains, thus adjusting the superlattice period. We also show that the quasiperiodicity can suppress coherent phonon transport in these superlattices. We attribute this behavior to the increased inhomogeneity in the distribution of interfaces, which increases for each Fibonacci generation, hindering coherent phonon transport in the superlattices. The suppression of coherent thermal transport enables a higher degree of control on heat conduction at the nanoscale, and shows potential for application in thermoelectric devices and heat management.