Non-Fermi liquid and Mott transition in the multi-channel two-band Hubbard model in infinite dimensions

Abstract

Electronic states in the single- and multi-channel two-band Hubbard models in infinite spatial dimensions are investigated by using the self-consistent 1/ N-expansion method which is a conserving approximation based on the perturbation expansion from the large limit of the spin–orbital degeneracy N. It is shown that a metallic state in the single-channel model behaves as a Fermi liquid, where imaginary part of self-energy of quasi-particles is proportional to ω 2+(π T) 2, while a metallic state in the multi-channel model behaves as a non-Fermi liquid, where the imaginary part of the self-energy is finite even at ω= T=0. In each model with a half-filled band the Mott metal–insulator transition (MIT) is observed, when the charge transfer energy Δ is varied. When the system approaches the MIT point, effective mass of quasi-particles diverges in the single-channel model, while the total number of quasi-particles becomes zero in the multi-channel model.