We report measurements of the nonlinear conductance of InAs nanowire quantum dots coupled to superconducting leads. We observe a clear alternation between odd and even occupation of the dot, with sub-gap-peaks at ∣Vsd∣=Δ/e markedly stronger(weaker) than the quasiparticle tunneling peaks at ∣Vsd∣=2Δ/e for odd(even) occupation. We attribute the enhanced Δ-peak to an interplay between Kondo-correlations and Andreev tunneling in dots with an odd number of spins, and substantiate this interpretation by a poor man's scaling analysis.
@article{arxiv.cond-mat/0703264,
title = {Kondo-Enhanced Andreev Tunneling in InAs Nanowire Quantum Dots},
author = {T. Sand-Jespersen and J. Paaske and B. M. Andersen and K. Grove-Rasmussen and H. I. Jørgensen and M. Aagesen and C. Sørensen and P. E. Lindelof and K. Flensberg and J. Nygård},
journal= {arXiv preprint arXiv:cond-mat/0703264},
year = {2009}
}