The magnetoresistance of a PrFeAsO_1-xF_y superconductor

Abstract

We have measured the temperature and magnetic field dependence of resistivity of polycrystalline PrFeAsO_0.60F_0.12 samples in the normal and superconducting state. The superconducting onset transition temperature Tcon shifts by ∼4 K as H is increased from 0 to 14 T. The zero-temperature upper critical field H_c2(0) estimated by using the Ginzburg–Landau theory and the Werthamer–Helfand–Hohenberg equation exceeds 100 T. 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 ∝ 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.