Berlin 2005 – scientific programme

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TT: Tiefe Temperaturen

TT 3: Correlated Electrons - Heavy Fermions

TT 3.10: Talk

Friday, March 4, 2005, 12:30–12:45, TU H3027

Kondo-lattice type models at finite temperatures with exact diagonalzation — •Ivica Zerec, Burkhard Schmidt, and Peter Thalmeier — Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden

The competition between the RKKY interaction and the Kondo screening in heavy fermion compounds is considered to be the origin of quantum critical phase transitions. They are generically described by the Doniach phase diagram, which was originally obtained from a simplified version of the Kondo lattice model in one dimension - the Kondo necklace model. We consider a similar model for the 2D systems, derived from the Kondo lattice model neglecting charge degrees of freedom. We use the finite temperature Lanczos method to numerically diagonalize the Hamiltonian matrix for finite clusters and calculate thermodynamic and correlation functions for various values of the coupling constants and the external magnetic field. The results are used to construct the phase diagrams for the finite clusters. These may provide some insight into the physics in the neighborhood of a quantum critical point.