Fabry-Perot interference, Kondo effect and Coulomb blockade in carbon nanotubes

TL;DR

This paper explores quantum transport phenomena in high-quality single wall carbon nanotube quantum dots, revealing transitions from wave-like interference to Coulomb blockade and Kondo effects, with detailed experimental observations.

Contribution

It demonstrates the coexistence and transition between Fabry-Perot interference, Coulomb blockade, and Kondo regimes in carbon nanotube quantum dots, highlighting new intermediate behaviors.

Findings

Observation of Fabry-Perot interference in nanotubes

Identification of Coulomb blockade oscillations

Detection of SU(4) Kondo regime in intermediate states

Abstract

High quality single wall carbon nanotube quantum dots have been made showing both metallic and semiconducting behavior. Some of the devices are identified as small band gap semiconducting nanotubes with relatively high broad conductance oscillations for hole transport through the valence band and low conductance Coulomb blockade oscillations for electron transport through the conduction band. The transition between these regimes illustrates that transport evolves from being wave-like transmission known as Fabry-Perot interference to single particle-like tunneling of electrons or holes. In the intermediate regime four Coulomb blockade peaks appear in each Fabry-Perot resonance, which is interpreted as entering the SU(4) Kondo regime. A bias shift of opposite polarity for the Kondo resonances for one electron and one hole in a shell is in some cases observed.