Paraconductivity of doped LaOFeAs superconductors

The paraconductivity of both electron- and hole-doped LaOFeAs superconductors is studied within the existed fluctuation mechanisms. It is found that the FC data at the temperature close to T_c can be explained with the three-dimensional (3D) Aslamazov-Larkin (AL) theory. The Gaussian-Ginzburg-Landau (GGL) approach under various cutoff conditions can only account for the fluctuation conductivity (FC) data in the 3D AL regime. While the approach taking into account the pseudogap effect can describe the paraconductivity very well in the whole temperature region. This result suggests that the pseudogap state of doped LaOFeAs system is probably due to the formation of paired fermions in the form of strongly bound bosons (local pairs) at T_c<T<T^∗.