Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 16: Korrelierte Elektronen: Quantenstörstellen, Kondo-Physik
TT 16.3: Vortrag
Dienstag, 9. März 2004, 17:15–17:30, H19
Quantum Phase Transitions in Models of Magnetic Impurities — •Hyun Jung Lee1, Ralf Bulla1, Ning-Hua Tong1, and Matthias Vojta2 — 1Theoretische Physik III, Universität Augsburg — 2Institut für Theorie der Kondensierten Materie, Universität Karlsruhe
The numerical renormalization group method is used to investigate zero temperature phase transitions in single-impurity models, where an impurity couples to a non-trivial fermionic bath (Pseudogap Anderson model) or to a (sub)ohmic bosonic bath (Spin-Boson Model). In both cases, zero temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However the quantum critical point cannot be described by non-interacting fermionic or bosonic excitation. To understand the quantum critical behavior, we study the character of the different fixed points as well as thermodynamic quantities such as entropy and specific heat.