Regensburg 2004 – wissenschaftliches Programm
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SYNF: Non-Fermi Liquids in Quantum Structures
SYNF 1: Non-Fermi Liquids in Quantum Structures
SYNF 1.4: Hauptvortrag
Donnerstag, 11. März 2004, 16:45–17:20, H 1
A carbon nanotube quantum dot coupled to superconductors — •Mark Buitelaar1,2, Bakir Babic2, Wolfgang Belzig2, Christoph Bruder2, Thomas Nussbaumer2, and Christian Schönenberger2 — 1Cavendish Laboratory, Madingley Road, CB3 0HE, Cambridge, United Kingdom — 2Institut für Physik, Universität Basel, Klingelbergstrasse 82, CH 4056 Basel, Switzerland
The electron spin is of central importance in two of the most widely studied many-body phenomena in solid-state physics: the Kondo effect and superconductivity. We have investigated their mutual interplay at the level of a single spin in a carbon nanotube quantum dot. The quantum dot can be changed from a non-Kondo to a Kondo system as the number of electrons on the dot is changed from even to odd. We demonstrate that the Kondo correlations on the dot are not destroyed by the superconductivity if the Kondo temperature, which varies for different single-electron states, exceeds the superconducting gap energy.
We observe multiple Andreev reflection peaks in the differential conductance. The position and magnitude of the subharmonic gap structure is found to depend strongly on the level positions of the single-electron states which are adjusted with a gate electrode. A theoretical model of the device reproduces some of the key features of the experimental data.