Non-Fermi-liquid behavior in a system with a nested Fermi surface

Abstract

The nesting of the Fermi surfaces of an electron pocket and a hole pocket separated by a wave vector Q interacting via a repulsive potential gives rise to itinerant antiferromagnetism. The order can gradually be suppressed by mismatching the nesting and a quantum critical point is obtained as T N →0. The renormalization group flow is studied by eliminating the fast degrees of freedom close to the ultraviolet cutoff, leading to a strong coupling fixed point. In the paramagnetic phase the system follows a Fermi liquid picture with a renormalized temperature dependent effective mass. The specific heat y coefficient and the uniform magnetic field susceptibility increase on a logarithmic scale when the temperature is lowered. The effective mass diverges at the critical point, signaling the breakdown of the Fermi liquid. The system is also unstable to singlet and triplet superconducting fluctuations. A strong magnetic field changes the nesting condition favoring one of the spin components, so that phases with spin- and charge-density waves and a ferromagnetic component can coexist. The results are discussed in the context of the non-Fermi-liquid behavior observed in some heavy fermion compounds.