k-space, Fysicum

Ultraclean carbon nanotubes form quantum dots of well-defined
atomic structure at low temperatures. Transport spectroscopy of ground and
excited states as a function of electron numbers in a parallel magnetic
field results in detailed
information about the band structures, in particular on spin-orbit and
KK'-mixing effects. This information is exploited in the analysis of the
SU(4) Kondo effect [1] occurring at larger electron numbers, where the
devices become more transmissive. The slightly broken fourfold degeneracy
in our device gives rise to satellites of the Kondo peak that shift in a
characteristic way in
perpendicular and parallel magnetic field. Our observations can be
understood in terms of the discrete symmetries of the carbon nanotubes,
and are well reproduced by state of the art theoretical modeling [2].

[1] P. Jarillo-Herrero et al., Nature 434, 484 (2005).

[2] S. Smirnov and M. Grifoni, Phys. Rev. B 87, 121302 (2013).

[1] P. Jarillo-Herrero et al., Nature 434, 484 (2005).

[2] S. Smirnov and M. Grifoni, Phys. Rev. B 87, 121302 (2013).