Thermal Transport Of Few-layer Twisted Graphene And Thermal Rectification Of Multi-terminal Graphene

Graphene has become one of the most attractive materials in recent years due to its excellent electrical,mechanical and thermal properties,which has great application prospects in various fields.At the same time,the study of thermal transport of low dimensional nano materials has gradually become the frontier subject of condensed matter physics.Graphene is the most widely known material with the highest thermal conductivity.It has important value in thermal conduction,thermal management and thermal energy utilization.In this thesis,the thermal transport properties of rotating graphene and the thermal rectification of multi-terminal graphene are studied.The results obtained provide the physical model and theoretical basis for the preparation of graphene based nano thermal devices.The thesis has been organized as follow.In the introduction,the background and objectives of the study are mainly introduced.In chapter two,the classical molecular dynamics method based on Newton's mechanics are introduced and derived.In this thesis,nonequilibrium molecular dynamics method is used to calculate the thermal transport properties of graphene.In third chapter,we investigate the inter layer and intra plane heat transport in multilayer graphene under different rotation angles by molecular dynamics.The inter layer and intra plane heat transport of graphene are more affected by the rotation angle,and when rotation angle is 30°,the interlayer coupling is lowest.Compared with the normal AB stacking,it can produce greater thermal insulation.This change is more pronounced when graphene gradually transition to the bulk.In forth chapter,the molecular dynamics method is used to calculate the heat rectification phenomena in multi-terminal graphene.The results show that the heat rectification in multi-terminal graphene is different with graphene nanoribbons.We can adjust the temperature of the terminal to change the rectifier efficiency.In summary,we summarize the work of this thesis,and make a brief prospect on the research of the heat transport of low dimensional nano materials.