Zero-bias conductance in carbon nanotube quantum dots

TL;DR

This paper uses numerical renormalization group calculations to analyze zero-bias conductance in carbon nanotube quantum dots, revealing universal scaling behaviors and matching experimental observations.

Contribution

It provides a detailed numerical study of conductance evolution in nanotube quantum dots, highlighting SU(4) universal scaling and its experimental validation.

Findings

Universal conductance scaling for SU(4) systems

Agreement with experimental conductance maps

Transition from Kondo to weakly correlated regimes

Abstract

We present numerical renormalization group calculations for the zero-bias conductance of quantum dots made from semiconducting carbon nanotubes. These explain and reproduce the thermal evolution of the conductance for different groups of orbitals, as the dot-lead tunnel coupling is varied and the system evolves from correlated Kondo behavior to more weakly correlated regimes. For integer fillings $N=1,2,3$ of an SU(4) model, we find universal scaling behavior of the conductance that is distinct from the standard SU(2) universal conductance, and concurs quantitatively with experiment. Our results also agree qualitatively with experimental differential conductance maps.