Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Postersession Correlated Electrons: (General) Theory, Low-Dimensional Systems, Kondo Physics, Heavy Fermions, Quantum-Critical Phenomena
TT 6.40: Poster
Montag, 23. März 2009, 13:00–16:45, P1A
Kondo model in and out of equilibrium: Functional RG at strong coupling — •Holger Schmidt and Peter Wölfle — Institut für Theorie der Kondensierten Materie, Universität Karlsruhe, D-76128 Karlsruhe, Germany
We apply the functional renormalization group (RG) method to calculate the conductance of a quantum dot in the Kondo regime in and out of equilibrium. The local spin 1/2 operator is described in pseudofermion representation. The set of of coupled RG equations for the pseudofermion self-energy and vertex functions in Keldysh space is derived and analyzed. Neglecting three-particle and higher vertex functions the equations are solved. It is found that the imaginary part of the self energy limits the growth of the two-particle vertex function at low temperatures and voltages T,V≪ TK (Kondo temperature), providing a semiquantitative description down into the strong coupling regime. In the regime max(T,V)≫ TK we recover the results of [1].
[1] A. Rosch et al., Phys. Rev. Lett. 90, 076804 (2003).
[2] J. Paaske et al., Phys. Rev. B, 70, 1553041 (2004).