Bulletin of the American Physical Society
76th Annual Meeting of the Southeastern Section of APS
Volume 54, Number 16
Wednesday–Saturday, November 11–14, 2009; Atlanta, Georgia
Session BA: Graphene and Nanotubes: Experiment and Theory |
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Chair: Laurie McNeil, University of North Carolina Room: Amsterdam |
Thursday, November 12, 2009 8:30AM - 9:00AM |
BA.00001: Massive Dirac fermions in sinle-layer graphene Invited Speaker: Motivated by the results of recent photoemission and tunneling studies, we discuss potential many-body sources of a finite gap in the Dirac fermion spectrum of graphene. Specifically, we focus on the putative Peierls- and Cooper-like pairing instabilities which can be driven by sufficiently strong Coulomb and electron-phonon interactions, respectively. Our results compare favorably with the available experimental and Monte Carlo data. [Preview Abstract] |
Thursday, November 12, 2009 9:00AM - 9:30AM |
BA.00002: Optical and Electronic Properties of Doped Carbon Nanotubes Invited Speaker: A carbon nanotube is an ideal prototype for probing the role of defects in nanoscale systems. Improved methods permit the synthesis of carbon nanotubes with controlled dopant (e.g., boron, nitrogen) concentrations. Raman spectroscopy has been widely used to study defects in sp2 carbon materials, including doping. Defects usually break the selection rules, so that broadening and new peaks can be observed in the Raman spectra mostly related to specific phonons in the interior of the Brillouin zone that are enhanced by a double-resonance process. Besides usual symmetry breaking effects, the presence of charged defects will renormalize the electron and phonon energies. We find that near a negatively charged defect the electron velocity is increased, which influences the atomic vibrations locally. Furthermore, Meissner effect exhibiting a Tc = 12 K is found in thin films consisting of assembled boron-doped single-walled carbon nanotubes (SWNTs). Superconductivity in boron-doped SWNTs and its correlation with dopant concentration will be presented. The first-principles electronic-structure study of boron-doped SWNTs strongly supports these results. [Preview Abstract] |
Thursday, November 12, 2009 9:30AM - 10:00AM |
BA.00003: Guiding electrons in carbon nanostructures using topological defects Invited Speaker: The paradox of perfection (i.e. flaws make things perfect) could be the key to designing nanoelectronic circuits from carbon nanostructures, such as nanotubes or graphitic nanoribbons. While individual carbon nanotubes can be exceptionally good conductors, connecting nanotubes into usable circuits is not easy, and in fact the networks realized from the connections between individual nanotubes do not conduct well. In this talk, I will present an overview of the studies we performed to determine the effect of topological defects on the electronic transport in complex carbon nanostructres. The theoretical findings will be compared to experimental data when available. First, I will present evidence that the transparency of nanojunctions can be improved dramatically by adding defects to the connecting ends of the nanonetworks. Second, I will show how these defects can be important for electrochemical energy storage applications. Finally, I will indicate how these findings can be used to devise practical devices with tailored properties. [Preview Abstract] |
Thursday, November 12, 2009 10:00AM - 10:30AM |
BA.00004: Epitaxial graphene: textbook non-interacting graphene Invited Speaker: Seamless multilayered epitaxial graphene layers are grown on the entire surface of SiC substrates by thermal decomposition of the SiC (000-1) C-face in a low vacuum induction furnace. This produces a new structure, consisting of a non-graphitic commensurate rotated stacking. This original layer stacking induces an effective decoupling of the layers, which preserves the integrity of the massless Dirac particles. This is experimentally demonstrated with linearly dispersing conical bands up to the Dirac point (ARPES), with the quantized Landau levels calculated for graphene (IR magneto-spectroscopy and scanning tunneling spectroscopy), a Berry's phase of pi, weak anti-localization and in the Raman spectra. Transport and spectroscopic measurements indicate high mobility, up to 250,000 cm2/Vs at room temperature. Epitaxial graphene can be patterned using standard lithography methods to define top and side- gated high mobility devices. Hundreds of transistors have been produced on a single mm2 size chip demonstrating the strong potential of multilayered epitaxial graphene for carbon-based electronic devices. [Preview Abstract] |
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