Average Density of States in Disordered Graphene systems

In this paper, the average density of states (ADOS) with a binary alloy disorder in disordered graphene systems are calculated based on the recursion method. We observe an obvious resonant peak caused by interactions with surrounding impurities and an anti-resonance dip in ADOS curves near the Dirac point. We also find that the resonance energy (Er) and the dip position are sensitive to the concentration of disorders (x) and their on-site potentials (v). An linear relation, not only holds when the impurity concentration is low but this relation can be further extended to high impurity concentration regime with certain constraints. We also calculate the ADOS with a finite density of vacancies and compare our results with the previous theoretical results.Comment: 10 pages, 8 figure

MS

thesisThis thesis is concerned with the electronic structure and transport property of disordered graphene. In Chapter 1, we begin with an introduction to graphene. Next, we introduce some types of disordered models that have been applied to graphene. Then, we discuss the theory for a disordered system, including localization and different transport regimes. Finally, we end up discussing the motivations of our work and give an outline of the thesis. In Chapter 2, we give an introduction to the recursion method. Then, we introduce the application of the recursion method in the calculation of the electronic structure and transport property. Finally, we end up discussing random phase approximation, which is used to accelerate the speed of the method. In Chapter 3, electronic structure of disordered graphene, mainly including the density of states, is first introduced. Then, we discuss the important parameters and show the accuracy in the calculation of density of states. Last, average density of states (ADOS) in graphene with binary alloy disorders are studied with the recursion method. In Chapter 4, we begin with an introduction to transport property of disordered graphene, mainly including the diffusion coefficient and conductivity. Next, we discuss the important parameters and show the accuracy in the calculation of transport property. Then, transport properties of graphene with short-range disorder and Coulomb disorder are studied with the recursion method. Finally, transport properties of graphene with vacancy are also investigated both in the absence and in the presence of a perpendicular magnetic field