Thermal rectification and negative differential thermal resistance behaviors in graphene/hexagonal boron nitride heterojunction

Thermal transport across graphene/hexagonal boron nitride (h-BN) nanoribbon interface is investigated using nonequilibrium molecular dynamics method. It is found that the heat current runs preferentially from the h-BN to graphene domain, which demonstrates pronounced thermal rectification behavior in this heterostructure. The observed phenomena can be attributed to the resonance effect between out-of-plane phonon modes of the graphene and h-BN domains in the low frequency region. In addition, we demonstrate that the optimum conditions for thermal rectification include low temperature, large temperature bias, short sample length and small interface densities. More interestingly, an unexpected negative differential thermal resistance (NDTR) behavior is also found at graphene/h-BN (CBN) nanoribbon interface with special edge geometry. Phonon spectra analysis reveals that the transverse acoustic wave plays an important role for the heat transfer at such interface.