New non-Fermi liquid type behavior given by a two-band system in normal phase

Abstract

We are reporting a new non-Fermi liquid type normal phase that has a well defined Fermi energy, but without showing any non-regularity in the momentum distribution function in the whole momentum space, the sharp Fermi momentum concept being undefinable. The system contains a natural built in gap that is visible in the physical properties of the system at nonzero temperatures. The presence of a flat band in multiband interacting Fermi systems with more than half filling is the key feature leading to such a ground state, which is not restricted to one spatial dimension and emerges in the proximity of an insulating phase.