Resistivity saturation in PrFeAsO_1-xF_y superconductor: Evidence of strong electron-phonon coupling

We have measured the resistivity of PrFeAsO_1-xF_y samples over a wide range of temperature in order to elucidate the role of electron-phonon interaction on normal-and superconducting-state properties. The linear T dependence of ρ above 170K followed by a saturation-like behavior at higher temperature is a clear signature of strong electron-phonon coupling. From the analysis of the T dependence of ρ, we have estimated several normal-state parameters that are useful for understanding the origin of superconductivity in this system. Our results suggest that Fe-based oxypnictides are phonon-mediated BCS superconductors like Chevrel phases and A15 compounds.