2000/07/06 by J. Kroha, P. Wölfle
Physics and Astronomy · #cond-mat.str-el
published as Adv. Solid State Phys. 39, 271 (1999) · Invited talk, March meeting of the German Physical Society, 1999, 10 pages, 5 figures, style file included
arxiv created 2000/07/06 · arxiv updated 2009/11/30
We review a recently developed method, based on an exact auxiliary boson representation, to describe both Fermi liquid and non-Fermi liquid behavior in quantum impurity systems. Coherent spin and charge fluctuation processes are taken into account in a self-consistent way and are shown to include \it all leading and subleading infrared singularities at any given order of the self-consistent loop expansion of the free energy. As a consequence, for the SU(N)× SU(M) Anderson impurity models the correct temperature dependence of the susceptibility is recovered over the entire temperature range, including Fermi liquid or non-Fermi liquid behavior below the Kondo temperature TK. As a standard diagram technique the presented method has the potential to be generalized to correlated electron systems on a lattice.