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TT: Tiefe Temperaturen

TT 16: Korrelierte Elektronen: Quantenstörstellen, Kondo-Physik

TT 16.2: Talk

Tuesday, March 9, 2004, 17:00–17:15, H19

Quantum Phase Transitions in the Fermi-Bose-Kondo and Pseudogap Kondo Models — •Matthias Vojta, Lars Fritz, and Marijana Kircan — Institut für Theorie der Kondensierten Materie,Universität Karlsruhe, D-76128 Karlsruhe

We discuss aspects of zero-temperature phase transitions in variations of the Kondo model, where fermionic Kondo screening can be suppressed due to the coupling to a bosonic bath or due to a gap in the fermionic density of states. In particular, we identify the lower and upper critical “dimensions” for the pseudogap Kondo model and present the field theories describing the critical behavior. We determine a number of universal properties near the impurity phase transitions and discuss applications to magnetic impurities in strongly correlated systems and to scenarios of local criticality in heavy-fermion compounds.