Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 34: Correlated Electrons - Quantum Impurities, Kondo Physics
TT 34.4: Vortrag
Mittwoch, 9. März 2005, 10:30–10:45, TU H104
Structure of Quantum Critical Points in Impurity Models — •Hyun-Jung Lee1, Ralf Bulla1, and Ning-Hua Tong2 — 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. These trivial phases are separated by lines of quantum critical points. The structure of these quantum critical points can be understood close to certain values of the bath exponents which turn out to play the role of upper and lower critical dimensions. A complete description of the quantum critical many-particle spectra is achieved using suitable marginal operators.