Low Temperature Physics: 39, 259 (2013); https://doi.org/10.1063/1.4795000 (6 pages)
Физика Низких Температур: Том 39, Выпуск 3 (Март 2013), c. 335-342    ( к оглавлению , назад )

Switchable zero-bias anomaly in individual C60 molecules contacted with tunable aluminum electrodes

E. Scheer1, T. Böhler1,*, A. Edtbauer1,**, S. Egle1, A. Erbe2, and T. Pietsch1

1Physics Department, University of Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany
E-mail: elke.scheer@uni-konstanz.de

2Institute for Ion Beam Physics, Helmholtz Center Dresden-Rossendorf Bautzner Landstraße 400, D-01328 Dresden, Germany

Received November 7, 2012


We report the observation of strong resonances at zero bias in the differential conductance through Al–C60–Al junctions with tunable electrode distance, measured above T = 10 K. The conductance value at resonance ranges from a few percent up to eighty percent of the quantum of conductance. The resonances may disappear or reoccur completely and discontinuously upon very small changes of the electrode distance. However, once they are formed they are very robust with respect to changes of the electrode distance. We discuss similarities and differences to the common theories of the Kondo screening of a spontaneous spin polarization of the C60 molecule. We deduce Kondo temperatures in the range from 35 to 160 K and demonstrate that the temperature dependence is in agreement with the scaling behavior of the Kondo effect in the temperature range of our experiment.

PACS: 73.63.–b Electronic transport in nanoscale materials and structures;
PACS: 73.23.–b Electronic transport in mesoscopic systems;
PACS: 74.70.Wz Carbon-based superconductors;
PACS: 85.65.+h Molecular electronic devices.

Key words: Kondo effect, fullerenes, point-contact spectroscopy, break-junctions.