A crossover in phase diagram of NaFe$_{1-x}$Co$_x$As determined by   electronic transport measurements
  We report electronic transport measurements on single crystals of NaFe$_{1-x}$Co$_x$As system. We found that the cotangent of Hall angle, cot$\theta_{\rm H}$, follows $T^4$ for the parent compound with filamentary superconductivity and $T^2$ for the heavily-overdoped non-superconducting sample. While it exhibits approximately $T^3$-dependence in all the superconducting samples, suggesting this behaivor is associated with bulk superconductivity in ferropnictides. A deviation develops below a characteristic temperature $T^*$ well above the structural and superconducting transitions, accompanied by a departure from power-law temperature dependence in resistivity. The doping dependence of $T^*$ resembles the crossover line of pseudogap phase in cuprates. 
A. F. Wang, J. J. Ying, X. G. Luo, Y. J. Yan, D. Y. Liu, Z. J. Xiang,   P. Cheng, G. J. Ye, L. J. Zou, Z. Sun, and X. H. Chen
cond-mat.supr-con