Electronic Properties of Graphene Nanoribbons

Physics of Atomic Nuclei - Nowadays, graphene physics is aimed at finding a way to control the band gap of graphene, which is necessary for application of graphene in nanoelectronics. The purpose...     

氧钝化石墨纳米带电子和光学性质的第一性原理

采用第一性原理方法,研究了氧原子钝化的扶手椅型石墨纳米带的结构、电磁特性和光学性质. 氧原子钝化的石墨纳米带比氢原子钝化稳定,显示出金属性质. 自旋极化计算的能带和态密度研究表明,该纳米带反铁磁态比铁磁态稳定,表现为反铁磁半导体特征. 由于边沿钝化的氧原子的影响,该系统的介电函数有明显的红移,且第一个介电峰主要由最高价带贡献. 介电函数、折射系数、吸收系数及能量损失等的峰值与电子跃迁吸收有关.     

三角形石墨烯纳米片电子和磁学性质的尺寸效应

基于密度泛函理论, 本文研究了氢钝化锯齿形边缘三角形石墨烯纳米片的电子结构和磁学性质, 这种石墨烯纳米结构的基态表现出强烈的磁性边缘态和量子尺寸效应。 我们应用多种交换关联泛函, 对体系的自旋密度和电子结构进行了第一性原理计算和理论分析, 结果表明三角形石墨烯纳米片的总磁矩和自旋随尺寸线性变化,平均磁矩随着尺寸变大而增加, 并逐渐趋于一个定值。 与此同时, 体系的能隙随着尺寸增加而减小, 其中自旋不变能隙的调控对光学响应和光子激发有着重要意义。 计算得到的单电子能谱表明, 费米能级的简并度与体系尺寸成正比。 应用多种交换关联泛函的计算结果表明, 三角形石墨烯纳米片具有可调控的自旋和能隙, 为其在纳米级光电器件和磁性半导体的应用方面提供了理论依据.     

Ab Initio Calculations of the Electronic Properties and the Transport Phenomena in Graphene Materials

Physics of the Solid State - The density functional theory (DFT) is used to study the electronic properties and the energy structure of monolayers of graphene supercells consisting of 18 and 54...     

Effect of Chemical Doping on the Electronic Transport Properties of Tailoring Graphene Nanoribbons

The electronic transport properties of a molecular junction based on doping tailoring armchair-type graphene nanoribbons(AGNRs)with different widths are investigated by applying the non-equilibrium Green's function formalism combined with first-principles density functional theory.The calculated results show that the width and doping play significant roles in the electronic transport properties of the molecular junction.A higher current can be obtained for the molecular junctions with the tailoring AGNRs with W=11.Furthermore,the current of boron-doped tailoring AGNRs with widths W=7 is nearly four times larger than that of the undoped one,which can be potentially useful for the design of high performance electronic devices.     

掺杂菱形BN片的石墨烯纳米带的电子特性

采用基于密度泛函理论的第一性原理方法,系统研究掺杂菱形BN片的石墨烯纳米带的电子特性.掺杂使扶手椅型石墨烯纳米带（AGNRs）的带隙增大,不同位置掺杂AGNRs的带隙大小略有差异.在无磁性态,无论是否掺杂,锯齿型石墨烯纳米带（ZGNRs）都为金属.在铁磁态,掺杂使ZGNRs由金属转变为半导体.而处于反铁磁态时,无论是否掺杂,ZGNRs都为半导体,掺杂使其带隙发生改变.掺杂的AGNRs和ZGNRs的结构稳定,掺杂ZGNRs的基态为反铁磁态.掺杂菱形BN片可以有效调控GNRs的电子特性.     

Geometry and Topology Induced Electronic Properties of Graphene Derived Quantum Systems

Three different topological structures built on the basis of a graphene lattice are investigated. Clusters of the (3,6) type homeomorphic with the sphere, toroidal, and cylindrical carbon nanotubes are shown to have the same dispersion relation, inherited from the planar graphene lattice. The persistent currents in axially symmetric structures, their dependence on the size and geometry of the molecule, are also discussed.     

Electronic Raman Scattering in Graphene

Linear dispersion near the Dirac points in the band structure of graphenes can give rise to novel physical properties. We calculate the electronic contribution to the Raman spectra in graphenes, which also shows novel features. In the clean limit, the Raman spectrum in the undoped graphene is linear （with a universal slope against impurity scattering） at low energy due to the linear dispersion near the Dirae points, and it peaks at a position corresponding to the van Hove singularity in the band structure. In a doped graphene, the electronic Raman absorption is forbidden up to a vertical inter-band particle-hole gap. Beyond the gap the spectrum follows the undoped case. In the presence of impurities, absorption within the gap （in the otherwise clean case） is induced, which is identified as the intra-band contribution. The Drude-like intra-band contribution is seen to be comparable to the higher energy inter-band Raman peak. The results are discussed in connection to experiments.     

Ab Initio Study of Structural,Electronic, and Elastic Properties of Graphene

Physics of the Solid State - Since its discovery in 2004, graphene has attracted the intention of several researchers in the world because of its fascinating electronic and mechanical properties....     

Effects of Stone-Wales Defect Symmetry on the Electronic Structure and Transport Properties of Narrow Armchair Graphene Nanoribbon

We report a first principles calculation to investigate the electron transport properties of defected armchair graphene nanoribbon (AGNR) influenced by Stone-Wales (SW) defect. The SW defect is found to be able to effectively influence the electronic structure of the defected AGNRs, and their electron transport behaviors can exhibit prominent differences depending on the symmetry of the nanostructured morphology. Moreover, our simulations have revealed that the introducing of the SW defect could be favorable for the electron transport of the defective AGNR. Our investigation has confirmed the possibility of tuning the electron transport of graphene nanoribbon by introducing a topological defect, which could be helpful to extending the field of applications for graphene nanoribbon-based nanodevices.     

Theoretical Study of the Electronic and Transport Properties of Lateral 2D–1D–2D Graphene–CNT–Graphene Structures

JETP Letters - The electronic and transport properties of new hybrid 2D–1D–2D structures of carbon atoms, which are graphene sheets continuously connected through a fragment of a...     

Massless Electronic Excitations in Graphene Near Coulomb Impurities

Journal of Experimental and Theoretical Physics - We study low-energy massless electronic excitations in a graphene monolayer near a pointlike Coulomb impurity. We assume that such excitations are...