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Imke Schneider1, Adel Benlagra1, Lars Fritz, and Matthias Vojta1
1) Institut für Theoretische Physik, Technische Universität Dresden 2) Institut für Theoretische Physik, Universität zu Köln We consider the multichannel Kondo problem with a pseudogap density of states ρ(ω)∝ |ω|r. Using renormalization group (RG) techniques we study the phase diagram and associated observables. In particular we combine both the Kondo language and the Anderson formulation of the problem which provides a comprehensive understanding of the general critical behavior. For small r a perturbative RG analysis of the Kondo coupling and potential scattering amplitude describes the phase transition between an unscreened local moment and a critical non-Fermi liquid fixed point. Notably, an additional line of fixed points found in numerical RG results cannot be captured by the weak coupling expansion in the Kondo coupling. To access the quantum phase transition near r=1 we use the Anderson formulation and apply an expansion in the hybridization strength. The calculated values for a number of observables agree well with numerical RG data. We relate our findings to experimental results on graphene. |
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