Normal state transport properties in single crystals of Ba1-xKxFe2As2 and NdFeAsO1-xFx

Hall effect and magnetoresistance Delta rho/rho(0) (MR) in the normal state have been measured oil single crystals of Ba1-xKxFe2As2 and NdFeAsO1-xFx. Detailed analysis reveal the following Conclusions: (1) For the parent phases of Ba1-xKx Fe2As2 and NdFeAsO1-xFx, large Hall effect and MR with strong temperature dependence were observed below a characteristic temperature corresponding to the anti ferromagnetic/structural transition. The field dependence of the Hall resistivity p, exhibits a non-linear behavior, which is accompanied by the violation of the B-square feature of the longitudinal magnetoresistivity, Delta rho(xx)(B)/rho(xx)(0). closer inspection further indicates that they are well related to each other and Could be attributed to the multi-band effect or spin-related scattering. (2) The superconducting samples show much smaller Hall coefficient and MR in the normal state. The Hall coefficient shows a weaker temperature dependence compared to the parent phase, while the mean scattering rate 1/tau(H) has a power-law like temperature dependence as 1/tau(H) proportional to T-n (n = 2-3). (3) For a Ba1-xKxFe2 As-2 sample with T-c = 36 K, the field dependence of MR is complicated and the feature varies in different temperature regions. A drastic change of Delta rho/rho(0) was found between 80 K and 100 K, which corresponds very well to the maximum of the temperature derivative of the resistivity. This may be attributed to the spin-related scattering of electrons. (4) A comparison between the parent phase and the superconducting sample with T, = 50 K in NdFeAsO1-xFx Suggests that the electronic transport properties in the normal state cannot be easily understood with the simple multi-band model, while a picture concerning a suppression to the quasiparticle density of states at the Fermi energy is more reasonable. (C) 2009 Elsevier B.V. All rights