Heat-pulse Rectification In Graphene Y Junctions: A Molecular Dynamics Simulations

Heat transport is closely related to our daily life. It is one of the basic ways to transport the energy in nature. Our body has good capability to control the heat transport, keeping the temperature of our organs in the optimum range. Could we manipulate the heat transport like the electricity? In recent years, the study of nanomaterials, especially the carbon nanomaterials, presents a positive answer. The basic control of heat is thermal rectification. In 1936, C. Starr found thermal rectification in a junction composed of a metallic copper and a cuprous oxide. In 2002, Terraneo et al. put forward the concept of thermal rectification on nanoscale. Then, in 2006, the first solid state thermal diode was fabricated in nanotube junction. After that, the idea of thermal rectification has attracted worldwide attention. In thermal rectification research field, the structure based on graphene, which has been found high thermal rectification ratio, has been given high expectations. By using non-equilibrium molecular dynamic simulation, this paper investigate the heat-pulse transport properties in graphene Y junctions. Our results demonstrate the existence of heat-pulse rectification in graphene Y junctions. Moreover, we find that the preferred heat pulse transport direction depends on the structure of the junctions. To clarify the underlying physical mechanism of the anisotropic heat-pulse flew through graphene Y junction, The paper further investigate the excited primary vibrational modes along the axial, transverse, and z-axis directions via the behavior of the vibrational amplitudes.In the first chapter of this paper, we briefly introduce the background of the manipulating of heat transport. In chapter II, we introduce the basic concepts of molecular dynamics simulations and the information of the simulation software package(LAMMPS). In chapter III, we introduce the basic properties and applications of graphene. Then, in chapter IV we investigate the heat-pulse rectification in two different graphene Y junctions and transport properties in an asymmetric graphene Y junction. Finally, we give a summary and an outlook in chapter V.