SU(4) Kondo Effect in Carbon Nanotubes

TL;DR

This paper theoretically explores the SU(4) Kondo effect in carbon nanotube quantum dots, revealing a four-peak splitting in conductance due to entangled spin and orbital degrees of freedom.

Contribution

It introduces the concept of an SU(4) Kondo effect arising from orbital and spin entanglement in carbon nanotubes, expanding understanding of multi-orbital Kondo phenomena.

Findings

Identification of SU(4) Kondo effect in nanotubes

Prediction of four-peak splitting in conductance

Analysis of magnetic field effects on the Kondo state

Abstract

We investigate theoretically the non-equilibrium transport properties of carbon nanotube quantum dots. Owing to the two-dimensional band structure of graphene, a double orbital degeneracy plays the role of a pseudo-spin, which is entangled with the spin. Quantum fluctuations between these four degrees of freedom result in an SU(4) Kondo effect at low temperatures. This exotic Kondo effect manifests as a four-peak splitting in the non-linear conductance when an axial magnetic field is applied.