\(1/(N - 1)\) Expansion for an SU(N) Impurity Anderson Model: A New Large-N Scheme Based on a Perturbation Theory in U
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Low-energy properties of an SU(N) Anderson model are studied, using the \(1/(N - 1)\) expansion based on a perturbation theory in the Coulomb interaction U. This approach is different from conventional large N theories, such as from the usual 1 ∕ N expansion and the non-crossing approximation based on the expansion in the hybridization matrix element between the impurity orbital and conduction band. In our approach the scaling factor N − 1 appears as the total number of interacting orbitals excluding the one prohibited by the Pauli principle, and it captures the low-energy local Fermi-liquid behavior correctly. We find that the next-leading-order results of the renormalized parameters agree closely with the numerical renormalization group results in a wide range of electron fillings at N = 4, where the degeneracy is still not so large. This ensures the reliability of the next-leading order results for N > 4. Furthermore, we apply this approach to nonequilibrium current through a quantum dot in the Kondo regime.
KeywordsAnderson Impurity Model Next-leading Order Hybridization Matrix Element Kondo Regime Numerical Renormalization Group (NRG)
The authors thank T. Kato and A.C. Hewson for discussions. This work is supported by the JSPS Grant-in-Aid for Scientific Research C (No. 23540375, and No. 24540316). Numerical computation was partly carried out at the Yukawa Institute Computer Facility.
- 9.Yamauchi Y, Sekiguchi K, Chida K, Arakawa T, Nakamura S, Kobayashi K, Ono T, Teruo, Fujii T, Sakano R (2011) Phys Rev Lett 106:17660Google Scholar