Incoherent non-Fermi-liquid scattering in a Kondo lattice

One of the most notorious non-Fermi-liquid properties of both archetypal heavy-fermion systems(1-4) and the high-T-c copper oxide superconductors(5) is an electrical resistivity that evolves linearly ( rather than quadratically) with temperature, T. In the heavy-fermion superconductor CeCoIn5 (ref. 6), this linear behaviour was one of the first indications of the presence of a zero-temperature instability, or quantum critical point. Here, we report the observation of a unique control parameter of T-linear scattering in CeCoIn5, found through systematic chemical substitutions of both magnetic and non-magnetic rare-earth, R, ions into the Ce sublattice. We find that the evolution of inelastic scattering in Ce1-xRxCoIn5 is strongly dependent on the f-electron configuration of the R ion, whereas two other key properties - Cooper-pair breaking and Kondo-lattice coherence - are not. Thus, T-linear resistivity in CeCoIn5 is intimately related to the nature of incoherent scattering centres in the Kondo lattice, which provides insight into the anomalous scattering rate synonymous with quantum criticality(7).