Nanotube Ropes Crossed Tube Junctions and Effects of Long Range Perturbations

Another interesting carbon nanotube system is that of ropes of single-walled carbon nanotubes which have been synthesized in high yield [8]. These ropes, containing up to tens to hundreds of single-walled nanotubes in a close-packed triangular lattice, are made up of tubes of nearly uniform diameter, close to that of the (10,10) tubes (Fig. 18). Because of the rather weak interaction between these tubes, a naive picture would be that the packing of individual metallic nanotubes into ropes would not change their electronic properties significantly. Theoretical studies [83,84,85] however showed that this is not the case for a rope of (10,10) carbon nanotubes. A broken symmetry of the (10,10) nanotube caused by interactions between tubes in a rope induces formation of a pseudogap in the density of states of about 0.1 eV. The existence of this pseudogap alters many of the fundamental electronic properties of the rope.

Fig. 18. Perspective view of a model of a rope of (10,10) carbon nanotubes

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