Non-Fermi liquid behavior in metals

Abstract

Metals are usually described within the framework of Fermi-liquid theory. Even heavy-fermion systems with their very large effective massm* derived from the huge linear specific-heat coefficient γ=C/T and a correspondingly large Pauli susceptibility χ can be regarded as Fermi-liquids withC/T ∼ χ=const. Recently, striking deviations from this behavior have been found in several heavy-fermion systems, e.g.C/T∼−ln(T/T0). This non-Fermi-liquid behavior may have different microscopic origins such as the single-ion quadrupolar Kondo effect, a collective effect caused by the incipient antiferromagnetic order or, simply a distribution of Kondo temperatures. Recent experiments will be reviewed with focus on the scenario of incipient magnetic order as exemplified in CeCu6−xAux.