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.
@article{arxiv.cond-mat/0411665,
title = {SU(4) Kondo Effect in Carbon Nanotubes},
author = {Mahn-Soo Choi and Rosa Lopez and Ramon Aguado},
journal= {arXiv preprint arXiv:cond-mat/0411665},
year = {2009}
}