We report on the electrical resistivity, thermoelectric power, and electronic phase diagram of rhodium-doped NdFeAsO. Rhodium doping suppresses the structural phase transition and spin-density wave observed in the undoped material, and superconductivity emerges at $x$ close to 0.05, despite the distortion of ${\text{FeAs}}_4$ tetrahedra induced by the large size difference between Rh and Fe elements. The $T_{\text{c}}\left(x\right)$ curve is domelike, and the highest $T_{\text{c}}$ is reached at $x=0.1$, with $T_{\text{c}}^{\text{onset}}=18\text{K}$. An upturn of the electrical resistivity above $T_{\text{c}}$ has been observed, with a Kondo-type behavior above $T_{\text{c}}$ and a Fermi-liquid behavior close to room temperature.

• Received 16 December 2009

DOI:https://doi.org/10.1103/PhysRevB.81.094506