Role of the d-f Coulomb interaction in intermediate valence and Kondo systems: a numerical renormalization group study
Institute of Metal Physics, Ekaterinburg, 620219, Russia
2 Institute for Molecules and Materials, Radboud University Nijmegen, 6525 ED Nijmegen, The Netherlands
Revised: 14 December 2006
Published online: 9 March 2007
Using the numerical renormalization group method, the dependences on temperature of the magnetic susceptibility χ(T) and specific heat C(T) are obtained for the single-impurity Anderson model with inclusion of d-f the Coulomb interaction. It is shown that the exciton effects caused by this effect (charge fluctuations) can significantly change the behaviour of C(T) in comparison with the standard Anderson model at moderately low temperatures, whereas the behaviour of χ(T) remains nearly universal. The ground-state and temperature-dependent renormalizations of the effective hybridization parameter and f-level position caused by the d-f interaction are calculated, and satisfactory agreement with the Hartree-Fock approximation is derived.
PACS: 71.27.+a – Strongly correlated electron systems; heavy fermions / 71.28.+d – Narrow-band systems; intermediate-valence solids / 75.30.Mb – Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007