Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 17: Postersitzung II: Mesoskopische Systeme (1-19), Supraleiter: Theorie (20-26), Elektronenstruktur, Phononen, Tunneln, Ordnungsparameter (27-33), Schwere Fermionen, Kondo-Systeme (34-45)
TT 17.5: Poster
Mittwoch, 13. März 2002, 14:30–18:00, A
Electrical transport in carbon-based molecular junctions — •Rafael Gutierrez1, Giorgos Fagas2, Giovanni Cuniberti3, Frank Grossmann1, Rüdiger Schmidt1, and Klaus Richter2 — 1Institut für Theoretische Physik, Technische Universität Dresden, Germany — 2Institut für Theoretische Physik, Universität Regensburg, Germany — 3Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
We study electron transport across a carbon molecular junction consisting of a C60 molecule sandwiched between two semi-infinite carbon nanotubes (CNT). The computational approach is based on the combination of a density-functional parametrized scheme for calculating the electronic structure with the Landauer transport formalism. We present results for both metallic (armchair) and semiconducting (zigzag) nanotubes used as leads. The influence of topological defects (pentagons) is investigated by closing the tubes’ surface facing the molecule with a cap. It is shown that the Landauer conductance of these carbon-based systems can be tuned within orders of magnitude not only by varying the tube–C60 distance, but more importantly at fixed distances by i) changing the orientation of the molecule or ii) rotating one of the tubes around its cylinder axis. Our results demonstrate that localized surface states related to dangling bonds (open CNT) or topological defects (closed CNT) have a strong impact on the transport by inducing resonant states within the HOMO-LUMO gap of the isolated C60. Finally, it is shown that structural relaxation qualitatively determines the transmission spectrum of such devices.