Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
Abstract
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