A crossover in phase diagram of NaFe$_{1-x}$Co$_x$As determined by electronic transport measurements
cond-mat.supr-con
/ Authors
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 1 more author
/ Abstract
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$θ_{\rm H}$, 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.