Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 44: Poster Session Correlated Electrons
TT 44.5: Poster
Thursday, March 17, 2011, 10:00–13:00, P1
Kondo effect in single wall carbon nanotubes with ferromagnetic contacts — Markus Gaass1, •Daniel Steininger1, Andreas K. Hüttel1, Kicheon Kang1,3, Ireneusz Weymann2,4, Jan von Delft2, and Christoph Strunk1 — 1Universität Regensburg, Germany — 2Ludwig-Maximilians-Universität München, Germany — 3Chonnam National University, Gwangju 500-757, Korea — 4Adam Mickiewicz University, 61-614 Poznań, Poland
We investigate the influence of ferromagnetic contacts on the Kondo effect in quantum dots formed in SWCNTs. For this purpose we use Pd0.3Ni0.7, a ferromagnetic alloy known for providing sufficiently transparent interfaces to CNTs [1,2].
Transport spectroscopy shows a conductance anomaly around zero bias in every second Coulomb diamond. The ferromagnetic contacts cause two peaks at finite bias which can be rejoined by a finite magnetic field. The size and sign of the splitting as well as its dependence on gate voltage can be explained by spin-dependent renormalization processes of the quantum dot level that include two contributions. One, independent of gate voltage, arises from the macroscopic magnetization of the leads. The other contribution, showing a gate dependence, stems from the polarization of the spins at the Fermi energy. The data are compared to numerical renormalization group calculations. In addition, we observe a fine structure in the spectra indicating a complex level structure which may result from curvature-induced spin-orbit interaction.
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