Thermal transport for flexural and in-plane phonons in graphene nanoribbons

The thermal transport properties of graphene nanoribbons with cavities are studied by non-equilibrium Green's function approach. A comparative analysis between in-plane and out-of-plane modes is made. The results show that the quantized thermal-conductance plateau of in-plane modes is wider and not broken in graphene nanoribbon with cavities. Contribution of the out-of-plane modes to the total thermal conductance increases with low temperature and decreases with high temperature for perfect graphene nanoribbons. However, the cavities make this contribution down at low temperatures.