Interference effects in electronic transport through metallic single-wall carbon nanotubes

TL;DR

This paper theoretically investigates electronic transport in metallic single-wall carbon nanotubes, revealing interference effects and conductance patterns that include diamond structures and novel features like double-diamond sub-structures.

Contribution

It introduces a real-space theoretical approach to analyze interference effects in nanotube conductance, accounting for contact quality and electronic structure within a tight-binding model.

Findings

Conductance exhibits diamond-like patterns similar to experiments.

Identification of new features such as double-diamond sub-structures.

Theoretical confirmation of interference effects in nanotube transport.

Abstract

In a recent paper Liang {\it et al.} [Nature {\bf 411}, 665 (2001)] showed experimentally, that metallic nanotubes, strongly coupled to external electrodes, may act as coherent molecular waveguides for electronic transport. The experimental results were supported by theoretical analysis based on the scattering matrix approach. In this paper we analyze theoretically this problem using a real-space approach, which makes it possible to control quality of interface contacts. Electronic structure of the nanotube is taken into account within the tight-binding model. External electrodes and the central part (sample) are assumed to be made of carbon nanotubes, while the contacts between electrodes and the sample are modeled by appropriate on-site (diagonal) and hopping (off-diagonal) parameters. Conductance is calculated by the Green function technique combined with the Landauer formalism. In the plots displaying conductance {\it vs.} bias and gate voltages, we have found typical diamond structure patterns, similar to those observed experimentally. In certain cases, however, we have found new features in the patterns, like a double-diamond sub-structure.