Nowadays sp carbon chains terminated by graphene or graphitic-like carbon are synthesized routinely in several nanotech labs.
We propose an ab-initio study of such carbon-only materials, by computing their structure and stability, as well as their electronic, vibrational and magnetic properties.
We adopt a fair compromise of microscopic realism with a certain level of idealization in the model configurations, and predict a number of properties susceptible to comparison with experiment.
Periodic Behavior of Topology in Graphene with Nanohole Array
Institute for Quantum Science and Technology, and Department of Physics, Shanghai University(上海大学量子科学与技术研究院及物理系);School of Engineering, Institute of Science Tokyo(东京科学大学工程学院)
Owing to its array of unique properties, graphene is a promising material for a wide variety of applications. Being two-dimensional, the properties of graphene are also easily tuned via proximity to other materials. In this work, we investigate the possibility of inducing electrical and optical anisotropy in graphene by interfacing it with other anisotropic carbon systems, including nanoporous graphene and arrays of graphene nanoribbons. We find that such materials do indeed induce such anisotropy in graphene, while also preserving the unique properties offered by graphene's Dirac band structu…
Allotropes of carbon, including one-dimensional carbon nanotubes and two-dimensional graphene sheets, continue to draw attention as promising platforms for probing the physics of electrons in lower dimensions. Recent research has shown that the electronic properties of graphene multilayers are exquisitely sensitive to the relative orientation between sheets, and in the bilayer case exhibit strong electronic correlations when close to a magic twist angle. Here, we investigate the electronic properties of a carbon nanotube deposited on a graphene sheet by deriving a low-energy theory that accoun…
We study Coulomb drag in a system consisting of a carbon nanotube (CNT) and monolayer graphene. Within the Fermi liquid theory we calculate the drag resistivity and find that the dimensional mismatch of the system components leads to a dependence of the drag rate on the carrier density, temperature, and spacing, which is substantially different from what is known for graphene double layers. Due to the competing effects of forward and backward scattering, we identify new features of the drag dependence on the electron density, which allows us to control their relative contribution to the drag r…
Graphene with its dispersion relation resembling that of photons offers ample opportunities for applications in electron optics. The spacial variation of carrier density by external gates can be used to create electron waveguides, in analogy to optical fiber, with additional confinement of the carriers in bipolar junctions leading to the formation of few transverse guiding modes. We show that waveguides created by gating graphene with carbon nanotubes (CNTs) allow obtaining sharp conductance plateaus, and propose applications in the Aharonov-Bohm and two-path interferometers, and a pointlike s…
Exploring the mechanism of interfacial thermal transport and reducing the interfacial thermal resistance is of great importance for thermal management and modulation. Herein, the interfacial thermal resistance between overlapped graphene nanoribbons is largely reduced by adding bonded carbon chains by performing molecular dynamics simulations. And the analytical model (cross-interface model, CIM) is utilized to analyze and explain the two-dimensional thermal transport mechanism at cross-interface. An order of magnitude reduction in interfacial thermal resistance is found as the graphene nanori…
We have measured Coulomb drag between an individual single-walled carbon nanotube (SWNT) as a one-dimensional (1D) conductor and the two-dimensional (2D) conductor monolayer graphene, separated by a few-atom-thick boron nitride layer. The graphene carrier density is tuned across the charge neutrality point (CNP) by a gate, while the SWNT remains degenerate. At high temperatures, the drag resistance changes sign across the CNP, as expected for momentum transfer from drive to drag layer, and exhibits layer exchange Onsager reciprocity. We find that layer reciprocity is broken near the graphene C…
Elementary electronic excitations, which are due to the Coulomb-field scatterings, present the diverse phenomena in 3D, 2D, 1D-nanotube electron gases, graphene and carbon nanotubes. The critical mechanisms cover the dimension-dependent bare Coulomb potentials, energy dispersions, and free/valence carrier density. They are responsible for the main features, the available excitation channels (the electron-hole regions), the joint van Hove singularities, the undamped/damped collective excitations at small/sufficiently high transferred momenta, the momentum dependences of plasmon frequencies (aco…
We use the robust nearest-neighbour tight-binding approximation to study on the same footing interband dipole transitions in narrow-bandgap carbon nanotubes and graphene nanoribbons. It is demonstrated that curvature effects in metallic single-walled carbon nanotubes and edge effects in gapless graphene nanoribbons not only open up bang gaps, which typically correspond to THz frequencies, but also result in a giant enhancement of the probability of optical transitions across these gaps. Moreover, the matrix element of the velocity operator for these transitions has a universal value (equal to …
Carbon Impurities on Graphene Synthesized by Chemical Vapor Deposition on Platinum
我们报告了纳米晶碳杂质与通过化学气相沉积(CVD)在铂上合成的石墨烯共存。我们观察到微米尺寸的岛状杂质层,其在光学显微镜或次级电子显微镜(SEM)中容易被误认为第二石墨烯层。岛的取向取决于Pt的结晶取向,如电子背散射衍射(EBSD)所示,表明石墨烯下方的无定形碳的生长。暗场TEM表明,除了均匀的单晶石墨烯之外,我们的样品还装饰有空间不均匀分布的纳米晶碳杂质。拉曼光谱显示出大的D峰,然而电特性显示出高迁移率(~ 6,000 cm 2/Vs),表明拉曼光谱在表征石墨烯的电子质量方面的局限性。
The main research efforts are aimed at finding inexpensive materials that can be converted into nanostructured carbon-containing materials, such as activated carbon and graphene. Rice husks are one such material, especially in developing countries, where more than 95% of Rice husks are produced worldwide. Although numerous studies have been conducted on the production of activated carbon and graphene structures from Rice husk, the existing scientific information is still widely scattered in the literature. Therefore, this review article provides extensive information on made by various researc…