Transport through single-wall metallic carbon nanotubes in the cotunneling regime

TL;DR

This paper investigates electron transport in single-wall metallic carbon nanotubes using advanced theoretical techniques, revealing how conductance, noise, and magnetoresistance depend on electron filling and tunneling processes.

Contribution

It provides a comprehensive analysis of transport properties considering both sequential and cotunneling, highlighting the impact of shell filling schemes on observable phenomena.

Findings

Shot noise is super-Poissonian in even occupation Coulomb diamonds.

Tunnel magnetoresistance varies significantly with electron number and shell filling.

Theoretical results align with recent experimental observations.

Abstract

Using the real-time diagrammatic technique and taking into account both the sequential and cotunneling processes, we analyze the transport properties of single-wall metallic carbon nanotubes coupled to nonmagnetic and ferromagnetic leads in the full range of parameters. In particular, considering the two different shell filling schemes of the nanotubes, we discuss the behavior of the differential conductance, tunnel magnetoresistance and the shot noise. We show that in the Coulomb diamonds corresponding to even occupations, the shot noise becomes super-Poissonian due to bunching of fast tunneling processes resulting from the dynamical channel blockade, whereas in the other diamonds the noise is roughly Poissonian, in agreement with recent experiments. The tunnel magnetoresistance is very sensitive to the number of electrons in the nanotube and exhibits a distinctively different behavior depending on the shell filling sequence of the nanotube.