Electronic transport in carbon nanotube junctions

Features of the ballistic electron transport through a network of carbon nanotubes provide an important basis for the design of future 'nanotube devices'. As the first step toward the elucidation of these features, we studied reflection and transmission of electron waves at a number of junctions of two metallic carbon nanotubes with different diameters. Geometrical structures of the junctions are determined by the relative arrangement of a pair of a five membered ring and a seven membered ring on the development map. The transmission coefficients are calculated by a tight binding scattering wave method for more than eight hundreds of different junctions, and a remarkable scaling law was found. The conductance sigma calculated by the Landauer's formula depends only on i/R, where R and i are the circumference of the thinner tube and the length of the junction, respectively. For the larger i/R, sigma depends as (i/R)(-3). (C)1997 Elsevier Science Ltd.