Regensburg 2004 – scientific programme
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TT: Tiefe Temperaturen
TT 16: Korrelierte Elektronen: Quantenstörstellen, Kondo-Physik
TT 16.4: Talk
Tuesday, March 9, 2004, 17:30–17:45, H19
Lattice path integral approach to the Kondo problem — •Michael Bortz1 und Andreas Klümper2 — 1Universität Dortmund, Fachbereich Physik, Lehrstuhl T1, 44221 Dortmund — 2Bergische Universität Wuppertal, Fachbereich Physik, 42097 Wuppertal
We propose a lattice regularization of the one-dimensional isotropic single channel spin-1/2 Kondo model, including the host and the impurity. From symmetry arguments, effective models for the more general anisotropic m-channel spin-S case are given. By application of the Quantum Transfer Matrix formalism, we obtain the free energy and other thermodynamic equilibrium response functions exactly by a set of max(2S,m)+1 non-linear integral equations. These are studied analytically in certain limiting ranges of the external parameters (temperature and magnetic field) and numerically over wide parameter ranges. Both high- and low-temperature scales (Wilson ratios) are calculated; especially, the ratios relating the regimes of high- and low-temperatures are derived for the first time in the framework of an exact solution.