Electrical transport in carbon nanotubes and quantum wires:
experiments and theoretical results
We present computational results on the electronic structure and transport properties of covalently bonded quantum wires: carbon nanotubes and carbon atom chains. Issues such as the length dependence of the conductance of short atomic wires, the role of charge-transfer doping, and the distributions of the charge within the wires will be discussed. The effects of structural distortions on the conductance of wires and nanotubes will also be analyzed. The experimental studies will focus on the low temperature transport properties of single wall carbon nanotubes (SWNTs). The effective 1D character of SWNTs does not allow magneto-resistance (MR) techniques to be applied directly in their study. Recently, however, we have found ways to prepare rings of SWNTs. These rings have the required topology for MR studies. Using MR we found that the rings are in a state of weak localization over a wide temperature range (3-60K). The coherence lengths are large, reaching a value of ~0.5 mm at 3K. The dominant dephasing mechanism at low T is found to involve electron-electron interactions. A clear transition from a weakly to a strongly localized state is observed below ~1 K. Finally, evidence of Kondo-type scattering is obtained below ~0.7 K.
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Last modification: 1999.07.15 (Thursday) 11:32:04 EDT