Temperature dependence of resistivity of RFeAsO compounds

The resistivity (q) data for RFeAsO compounds(R = Ce, Pr, Nd, Sm), in the temperature (T) range35–315 K have been analyzed to identify the dominantscattering mechanisms. Close to the room temperature, thesystem appears to be a metal with low electron density, andthe electron–phonon scattering is the dominant one. Atlower temperatures, electron–electron scattering plays animportant role. In an intermediate temperature region,unlike metallic system, dq/dT is negative; and q(-1) varies asln T as in a state of weak localization. We look into theorigin of negative dq/dT. The analysis of q(T) data belowthe SDW transition temperature shows the presence ofelectron–electron interaction in addition to a SDW energygap, and also gives an estimate of the SDW energy gap.