Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

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.