Special Theory Seminar | August 17, 15:00
Spin and Charge Correlations in Quantum Dots: An Exact Solution
The inclusion of charging and spin-exchange interactions within the
Universal Hamiltonian description of quantum dots is a highly non-trivial
problem owing to the fact that it leads to a formulation of the problem in terms
of a non-Abelian action. We present an exact analytical solution of the problem,
in particular, in the vicinity of the Stoner instability point. We calculate exactly
several physical observables, including the tunneling density of states (TDOS)
and the spin susceptibility. We find that due to the presence of spin-exchange
interaction, at the vicinity of the instability point the TDOS exhibits a non-monotonous
behavior as function of the tunneling energy. This effect survives even at
temperatures much higher than the exchange energy. Also, we find that in
the same temperature range the single-particle level fluctuations enhances
the spin-susceptibility in the vicinity of the Stoner instability. Experimentally,
our results could be tested in nearly ferromagnetic materials. Some of the
results are published in I.S. Burmistrov, Yu. Gefen, M.N. Kiselev, JETP Lett. 92, 766 (2010).
Landau Institute for Theoretical Physics, Moscow
Seminarraum Theoretische Physik
Contact: not specified