Infrared Divergence and Non-Fermi Liquid in Multichannel Degenerate Anderson Model

Abstract

As a straightforward extention of the study on infrared divergences in pseudo-particle spectra in the single-channel degenerate impurity Anderson model, those of the multichannel model are examined with use of the expansion from the large limit of the spin-orbital degeneracy N. Analysis with the most divergent terms in the expansion shows that exponents of spectra of the slave boson and the pseudo-fermion in the M-channel model with 1 ≤ M << N are given respectively by 1-n_f²M/N and (2n_f-n_f²)M/N, where n_f is the average number of localized electrons at the impurity site. When M=1, the results recover those obtained earlier in the single channel model. In the limits, n_f → 1 and M^-2 << 1, these results tend to those obtained by the non-crossing approximation (NCA) study. It also shows that the scattering rate of the conduction electrons in the M-channel model includes infrared divergent terms proportional to (1-n_f)(1-M^-2) in contrast to the absence of infrared divergent terms in the single-channel model.