Effect of Co doping on superconductivity and transport properties in   SmFe$_{1-x}$Co$_{x}$AsO
  We investigate superconductivity and transport properties of Co doped SmFe$_{1-x}$Co$_{x}$AsO system. The antiferromagnetic (AFM) spin-density wave (SDW) order is rapidly suppressed by Co doping, and superconductivity emerges as $x$ $\geq$ 0.05. $T_c$$^{mid}$ increases with increasing Co content, shows a maximum of 17.2 K at the optimally doping of $x\sim$ 0.10. A phase diagram is derived based on the transport measurements and a dome-like $T_c$ versus $x$ curve is established. Meanwhile we found that the normal state thermopower might consist of two different contributions. One contribution increases gradually with increasing $x$, and the other contribution is abnormally enhanced in the superconducting window 0.05 $\leq$ $x$ $\leq$ 0.20, and shows a dome-like doping dependence. A close correlation between $T_{c}$ and the abnormally enhanced term of thermopower is proposed. 
Y. K. Li, X. Lin, Z. W. Zhu, H. Chen, C. Wang, L. J. Li, Y. K. Luo, M.   He, Q. Tao, H. Y. Li, G. H. Cao, and Z. A. Xu