Resistivity scaling 1111 iron-pnictide superconductors

We show that the zero field normal-state resistivity above Tc for various levels of electron doping—both for LaO1−xFxFeAs (La-1111) and underdoped SmO1−xFxFeAs (Sm-1111) members of the 1111-iron-pnictide superconductor family—can be scaled in a broad temperature range from 20 to 300 K onto a single curve for underdoped La-1111 (x = 0.05–0.075), for optimally and overdoped La-1111 (x = 0.1–0.2) and for underdoped Sm-1111 (x = 0.06–0.1). It is found that the ρ(T  ) dependences can be reproduced by the formulas ρ(T)=ρ0+cTexp-2ΔT and ρ(T)=ρ0+(c/T)exp-2ΔT in the case of LaO1−xFxFeAs and SmO1−xFxFeAs, respectively. The scaling was performed using the energy scale 2Δ, c and the residual resistivity ρ0 as scaling parameters as well as applying a recently proposed model-independent scaling method [H.G. Luo, Y.H. Su, T. Xiang, Phys. Rev. B 77 (2008) 014529]. The scaling parameters have been calculated and the compositional variation of 2Δ has been determined. The observed scaling behavior for ρ(T) is interpreted as an indication of a common mechanism which dominates the scattering of the charge carriers in underdoped La-1111, in optimally and overdoped La-1111 and in underdoped Sm-1111.

► The normal-state resistivity ρ(T) of 1111 iron-pnictide crystals is analyzed. ► The resistivity exhibit good scaling behaviors. ► A common charge carriers scattering mechanism dominates in 1111 iron-pnictides.