Temperature versus Sm concentration phase diagram and quantum criticality in the correlated electron system Ce1-xSmxCoIn5

We report electrical resistivity, magnetization, and specific heat measurements on the correlated electron system Ce1-xSmxCoIn5 (0≤x≤1). Superconductivity (SC) in the heavy-fermion compound CeCoIn5, which is suppressed with increasing Sm concentration x, and antiferromagnetic (AFM) order of SmCoIn5, which is suppressed with decreasing x, converge near a quantum critical point at xQCP≈0.15, with no indication of coexistence of SC and AFM in the vicinity of the QCP. Non-Fermi-liquid (NFL) behavior is observed in the normal-state electrical resistivity, ρ(T), and specific heat, C(T), in the vicinity of the QCP; e.g., the coefficient and the exponent of the power-law T dependence of ρ(T) exhibit pronounced maxima and minima, respectively, at xQCP, while C(T)/T exhibits a logarithmic divergence in T at xQCP. A low-temperature upturn in ρ(T) develops in the range 0.70≤x≤0.85 which is reminiscent of a single impurity Kondo effect, suggesting that Sm substitution tunes the relative strength of competing Kondo and Ruderman-Kittel-Kasuya-Yosida energy scales. The suppression of SC with increasing x is probably associated with the exchange interaction between the Ce quasiparticles involved in the superconductivity and the magnetic moments of the Sm ions.