Effects of Co doping on the transport properties and superconductivity in CeFe_{1 - X}Co_xAsO

A series of CeFe_{1 - x}Co_xAsO oxyarsenide compounds with Co doping on iron sites (x = 0-0.2) have been synthesized by a solid state reaction method. The effects of Co doping on the electrical transport properties and superconductivity were analyzed with a special emphasis on the analysis of thermopower. Undoped CeFeAsO shows an electrical resistivity anomaly at about 150K, which was ascribed to a spin-density-wave (SDW) instability. This anomaly is suppressed and a superconducting transition occurs at T_c = 3.2K in CeFe_0.95Co_0.05AsO, the maximum superconducting transition temperature (T_c) of 12.5K is observed in CeFe_0.90Co _0.10AsO, and the thermopower is increased by the Co doping. As has been previously suggested, the emergence of superconductivity seems to be closely linked to the thermopower, and there is a close correlation between T_c and the thermopower, both showing a similar dome-like doping dependence.