Breakdown of the Fermi-liquid regime in the two-dimensional Hubbard model from a two-loop field-theoretical renormalization group approach

摘要

We analyze the particle-hole symmetric two-dimensional Hubbard model on a square lattice starting from weak-to-moderate couplings by means of the field-theoretical renormalization group approach up to two-loop order. This method is essential in order to evaluate the effect of the momentum-resolved anomalous dimension η(p) which arises in the normal phase of this model on the corresponding low-energy single-particle excitations. As a result, we find important indications pointing to the existence of a non-Fermi-liquid (NFL) regime at temperature T→0 displaying a truncated Fermi surface (FS) for a doping range exactly in between the well-known antiferromagnetic insulating and the d_(x~2-y~2)-wave singlet superconducting phases. This NFL evolves as a function of doping into a correlated metal with a large FS before the d_(x~2-y~2)-wave pairing susceptibility finally produces the dominant instability in the low-energy limit.