Topological Properties Of Three-dimensional Carbon Materials Based On Two-dimensional Thin Films

Since the graphene was successfully synthesized,various two-dimensional carbon allotropes have been proposed.These two-dimensional materials exhibit excellent physical and chemical properties.For example,it has been found that there are Dirac electrons in graphene and graphyne.On the other hand,topological materials are the hotspot of condensed matter physics research in recent years.However,compared to three-dimensional materials,two-dimensional structures cannot be found in many topological phases due to the limitations of their Brillouin zone dimensions.Therefore,we can use the excellent properties of two-dimensional materials to construct threedimensional structures,and discover more interesting electronic properties and topological phenomena.Experimentally,a three-dimensional honeycomb carbon network formed by cross-linking of graphene or graphene nanoribbons has been successfully synthesized,and a topological phase such as a nexus point is found therein.It is expected that a rich three-dimensional carbon network can be obtained based on various two-dimensional carbon allotropes.This paper will study the electronic structure and topological properties of these new three-dimensional carbon networks.The paper is divided into the following five chapters:The first chapter introduces the research background of carbon materials,and introduction topological theory and typical topological phase and related research.The second chapter introduces the first-principles method for calculating actual materials and the tight-binding method for calculating the electronic properties of models.The third chapter,we propose a new topological phase—interlocking nodal chains,which is made of two sets of nodal chain interlocking each other.Based on this topological phase,we also propose a series of related topological phases.These topologies have different topological surface states and also exhibit new features at the Landau level.In addition,we can be found this new topological phase in carbon networks consisting of graphene armchair chains.Finally,we also provide a theoretical method to synthesize a three-dimensional carbon network.The fourth chapter,we propose two three-dimensional carbon network structures based on Kagome graphene—three-dimensional Kagome graphene network,and analyze their electronic properties.The study found that they are all topological,and also found that the orbital frustration and two electron channels in the structure.That is to say,we can obtained stable three-dimensional carbon material by two-dimensional carbon film different from graphene and it has rich topological properties.In the fifth chapter,we summary the result of our study and described the future of study.