Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 6: TR: Nanoelectronics II: Spintronics and Magnetotransport

TT 6.2: Talk

Monday, March 22, 2010, 14:15–14:30, H19

Kondo Effect in single wall carbon nanotubes with ferromagnetic contacts — •Markus Gaaß, Andreas Hüttel, Dominik Preusche, Lorenz Herrmann, and Christoph Strunk — Universität Regensburg, Institut für Experimentelle und Angewandte Physik

We investigate the interplay of the Kondo effect and magnetic contacts in quantum dots formed by single wall carbon nanotubes. The regular spin-1/2 Kondo effect appears when the coupling between the electrodes and the quantum dot is high enough. If the leads are magnetized the Kondo resonance is exchange split at zero magnetic field. We fabricated single wall carbon nanotube transport devices with electric contacts made of PdNi which show a sufficient interface transparency to observe the Kondo effect. Without any applied field the Kondo resonance is indeed split. In some Coulomb valleys the splitting can be compensated by an external magnetic field on the order of 1 Tesla, in others it remains finite. In addition a fine structure in the spectra is observed which indicates a more complex level structure than expected for armchair carbon nanotubes.