Non-Fermi-liquid behavior due to nested Fermi surfaces: renormalization of the electron-phonon coupling and softening of phonons

The nesting of the Fermi surfaces of an electron pocket and a hole pocket separated by a wave vector Q and the interaction between electrons gives rise to spin- and charge-density waves (SDW and CDW). The order can gradually be suppressed by mismatching the nesting and a quantum critical point (QCP) is obtained as the critical temperature T-N --> 0. The renormalization group (RG) flow leads to a strong coupling fixed point. We study the enhancement of the electron-phonon coupling and the softening of the phonon with wave vector Q. The phonons couple to the charge-density waves giving rise to a Peierls distorted ground state. Close to an anti ferromagnetic (AF) instability the results are discussed in the context of non-Fermi-liquid (NFL) behavior observed in several heavy fermion compounds. (C) 2003 Elsevier B.V. All rights reserved.