Crystal growth and the electronic phase diagram of the 4\(d\) doped Na\(_{1-\delta}\)Fe\(_{1-x}\)Rh\(_x\)As in comparison with 3\(d\) doped Na\(_{1-\delta}\)Fe\(_{1-x}\)Co\(_x\)As

Single crystals of Na\(_{1-\delta}\)Fe\(_{1-x}\)T\(_x\)As with T = Co, Rh have been grown using a self-flux technique. The crystals were thoroughly characterized by powder X-ray diffraction, magnetic susceptibility and electronic transport with particular focus on the Rh-doped samples. Measurements of the specific heat and ARPES were conducted exemplarily for the optimally doped compositions. The spin-density wave transition (SDW) observed for samples with low Rh concentration (\(0\,\leq\,x\,\leq\,0.013\)) is fully suppressed in the optimally doped sample. The superconducting transition temperature (\(T_c\)) is enhanced from \(10\)~K in Na\(_{1-\delta}\)FeAs to \(21\)~K in the optimally doped sample (\(x\) = 0.019) of the Na\(_{1-\delta}\)Fe\(_{1-x}\)Rh\(_x\)As series and decreases for the overdoped compounds, revealing a typical shape for the superconducting part of the electronic phase diagram. Remarkably, the phase diagram is almost identical to that of Co-doped Na\(_{1-\delta}\)FeAs, suggesting a generic phase diagram for both dopants.