Fluctuation conductivity and pseudogap in optimally doped SmFeAsO(1-x)

We report the analysis of fluctuation conductivity (FLC) and pseudogap (D*) in Fe-based superconductor SmFeAsO0.85 with Tc = 55 K derived from resistivity experiments. In the FLC analysis distinct 2D-3D (MT-AL) crossover typical for cuprates but followed by enhanced MT fluctuation contribution was found. Using the crossover temperature To coherence length along c-axis Xc(0) was determined. Rather specific D*(T) dependence with two representative temperatures followed by minimum at about 125 K was observed. Below Ts = 147 K, corresponding to SDW ordering, D*(T) decreases linearly down to TAF = 133 K. This last peculiarity can likely be attributed to antiferromagnetic (AF) ordering in FeAs planes. It is believed that found behavior is strongly associated with specific electronic configuration of the Fe-based compounds