The magnetoresistance of a PrFeAsO_1-xF_y superconductor

We have measured the temperature and magnetic field dependence of resistivity of polycrystalline PrFeAsO_0.60F_0.12 samples in the normaland superconducting state. The superconducting onset transition temperature T_c^on shifts by ∼4K as H is increased from 0 to 14T. The zero-temperature upper critical field H_c2(0) estimated by using the Ginzburg-Landau theory and the Werthamer-Helfand-Hohenberg equation exceeds 100T. The resistivity below T_c^on exhibits Arrhenius behavior due to thermally activated flux flow of vortices. The activation energy U₀, determined from the Arrhenius plot of the resistivity, shows a power-law decrease (U₀ α H ^-α) with magnetic field. The normal-state magnetoresistance varies quasilinearly with magnetic field and does not obey Kohler's rule, suggesting a multiband feature of the material.