Lowest Landau level scaling of the fluctuation conductivity for RFeAsO (R=Nd,Pr,SmR=Nd,Pr,Sm) superconductors

The fluctuation conductivity under magnetic fields is studied in RFeAsO (R=Nd,Pr,SmR=Nd,Pr,Sm) superconductors reported in literatures within the lowest Landau level (LLL) scaling approach. The mean filed critical temperature Tc(H)Tc(H) is determined by the crossing point technique. With the determined values of Tc(H)Tc(H), the fluctuation conductivity is scaled within both three-dimensional (3D) and two-dimensional (2D) LLL approach. For all the samples studied, the 3D-LLL scaling is found but in a relatively small temperature interval around Tc(H)Tc(H), while 2D-LLL scaling is observed in all other temperature region. These results suggest a 3D–2D crossover of the fluctuation conductivity in RFeAsO superconductors.