Strongly correlated electron behavior: Superconductivity and non-Fermi liquid behavior in cerium-R-cobalt-indium

CeCoIn5 has received a great deal of attention in recent years due to its exotic normal state behavior and possibly magnetically mediated superconductivity. In this work, we performed a two-part doping study of CeCoIn5. First we investigated single crystals with dilute concentrations of several rare earths in the lanthanide series for Ce0:95R 0:05CoIn5. Second, in a more extensive substitution study, ytterbium was doped into the cerium sites for a full range of concentrations. For both cases, the synthesized compounds exhibited normal state NFL behavior, Kondo coherence, and magnetic anisotropy. In the rare earth study we found that the suppression of the superconducting transition Tc does not follow the conventional rate of suppression when a paramagnetic impurity is introduced into the system. In the ytterbium study a possible valence transition occurs for the Yb ion with increasing concentrations into the Ce sites. Single crystals of Ce0:95R0:05CoIn5 and Ce 1-xRxCoIn 5 are investigated by means of x-ray powder diffraction, resistivity as function of temperature, and magnetic susceptibility.