Temperature dependence of resistivity of RFeAsO compounds

The resistivity (ρ) data for RFeAsO compounds (R = Ce, Pr, Nd, Sm), in the temperature (T) range 35–315 K have been analyzed to identify the dominant scattering mechanisms. Close to the room temperature, the system appears to be a metal with low electron density, and the electron–phonon scattering is the dominant one. At lower temperatures, electron–electron scattering plays an important role. In an intermediate temperature region, unlike metallic system, dρ/dT is negative; and ρ −1 varies as ln T as in a state of weak localization. We look into the origin of negative dρ/dT. The analysis of ρ(T) data below the SDW transition temperature shows the presence of electron–electron interaction in addition to a SDW energy gap, and also gives an estimate of the SDW energy gap.