Modulated thermal transport for flexural and in-plane phonons in double-stub graphene nanoribbons**Project supported by the Science Funds from the Educational Bureau of Hunan Province, China (Grant No. 16C0468), the China Postdoctoral Science Foundation (Grant No. 2016M602421), the Science and Technology Plan of Hunan Province, China (Grant No. 2015RS4002), and the Natural Science Foundation of Hunan Province, China (Grant No. 2015JJ2050).

Abstract

Thermal transport properties are investigated for out-of-plane phonon modes (FPMs) and in-plane phonon modes (IPMs) in double-stub graphene nanoribbons (GNRs). The results show that the quantized thermal conductance plateau of FPMs is narrower and more easily broken by the double-stub structure. In the straight GNRs, the thermal conductance of FPMs is higher in the low temperature region due to there being less cut-off frequency and more low-frequency excited modes. In contrast, the thermal conductance of IPMs is higher in the high temperature region because of the wider phonon energy spectrum. Furthermore, the thermal transport of two types of phonon modes can be modulated by the double-stub GNRs, the thermal conductance of FPMs is less than that of IPMs in the low temperatures, but it dominates the contribution to the total thermal conductance in the high temperatures. The modulated thermal conductance can provide a guideline for designing high-performance thermal or thermoelectric nanodevices based on graphene.