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TT: Fachverband Tiefe Temperaturen

TT 10: Correlated Electrons: (General) Theory 1

TT 10.12: Vortrag

Montag, 26. März 2012, 18:00–18:15, H 3010

Heavy fermion properties in the Kondo lattice model — •Steffen Sykora¹ and Klaus W. Becker² — ¹IFW Dresden, Institute for Theoretical Solid State Physics, P.O. Box 270116, D-01171 Dresden, Germany — ²Technische Universität Dresden, Institut für Theoretische Physik, D-01062 Dresden, Germany

The Kondo lattice model is believed to describe the low-energy physics of heavy-fermion systems. It includes a band of conduction electrons, interacting via an exchange with a regular array of immobile spins S_i. No exact results are known for this model in any spatial dimension. We have studied the model using the quite novel projective renormalization method (PRM). Using this analytical technique we obtain a solvable effective Hamiltonian H which consists of conduction electrons with renormalized dispersion ε_k and an RKKY interaction term which is generated naturally within the renormalization procedure. The present approach allows us to evaluate static and dynamical properties such as the specific heat, the density of states or the electrical resistivity. For low enough temperatures we find an additional dispersionless excitation around the Fermi surface due to the formation of a singlet state. Simultaneously, a large γ-coefficient develops in the specific heat which is usually traced back to the huge effective mass of heavy fermion quasiparticles.