Non-Fermi liquid behavior in U and Ce intermetallics

In this paper we review the current experimental and theoretical situation of the description of non-Fermi liquid behavior (NFL) in U and Ce intermetallics. We focus on the magnetic and thermodynamic properties. We also discuss a recent theoretical interpretation of this behavior in terms of Griffiths-McCoy singularities close to the magnetic quantum critical point (QCP). We show how an effective Hamiltonian which contains both the RKKY coupling and the Kondo interaction can be written after high energy degrees of freedom away from the Fermi surface are traced out. We argue that dissipation due to particle-hole excitations close to the Fermi surface is a relevant perturbation at low temperatures and we estimate the crossover temperature T^* above which power law behavior in specific heat and magnetic response occurs ($C_V/T \sim \chi(T) \propto T^{-1+\lambda}$ with $\lambda<1$). Below T^* a new regime dominated by dissipation is found and deviations from power law behavior are expected.