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Quantum critical properties of the Bose-Fermi Kondo Model in a large-N limit

Lijun Zhu·Stefan Kirchner·Qimiao Si·Antoine Georges
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Abstract

Studies of non-Fermi liquid properties in heavy fermions have led to the current interest in the Bose-Fermi Kondo model. Here we use a dynamical large-N approach to analyze an SU(N)xSU($κN$) generalization of the model. We establish the existence in this limit of an unstable fixed point when the bosonic bath has a sub-ohmic spectrum ($|ω|^{1-ε} \sgn ω$, with $0<ε<1$). At the quantum critical point, the Kondo scale vanishes and the local spin susceptibility (which is finite on the Kondo side for κ<1) diverges. We also find an ω/T scaling for an extended range (15 decades) of ω/T. This scaling violates (for $ε\ge 1/2$) the expectation of a naive mapping to certain classical models in an extra dimension; it reflects the inherent quantum nature of the critical point.

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Lijun Zhu, Stefan Kirchner, Qimiao Si, Antoine Georges. 2005-01-06. Quantum critical properties of the Bose-Fermi Kondo Model in a large-N limit. https://doi.org/10.1103/physrevlett.93.267201

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