We present low-temperature electron transport measurements on a single-wall carbon nanotube quantum dot exhibiting Kondo resonances at low temperature. Contrary to the usual behavior for the spin-1/2 Kondo effect we find that the temperature dependence of the zero bias conductance is nonmonotonic. In nonlinear transport measurements low-energy splittings of the Kondo resonances are observed at zero magnetic field. We suggest that these anomalies reflect interactions between the nanotube and a magnetic (catalyst) particle. The nanotube device may effectively act as a ferromagnetically contacted Kondo dot.
@article{arxiv.cond-mat/0410467,
title = {Zero-field splitting of Kondo resonances in a carbon nanotube quantum dot},
author = {J. Nygard and W. F. Koehl and N. Mason and L. DiCarlo and C. M. Marcus},
journal= {arXiv preprint arXiv:cond-mat/0410467},
year = {2016}
}