سید نورالدین میرنیا

Excess fluctuation conductivity of BaFe1.9Co0.1As2 single crystal was studied by measurements of temperature and magnetic field dependence of resistance. The mean field critical temperature Tc (H) is determined by using the criterion of the dR/dT as a function of temperature, where a unique sharp peak appears in the dR/dT curves. By analyzing the excess fluctuation conductivity and the resistance experimental data in the framework of Aslamazov and Larkin theory, different fluctuation regimes such as the three-dimensional (3D), the two-dimensional (2D), the one-dimensional (1D), and short-wave fluctuation (SWF) were identified. In the mean field region, it was also found that the analyses of the resistance experimental data based on the Aslamazov-Larkin theory describes the real measured resistance data very well down to about 0.5 Rn at different regions, which supported the excess fluctuation conductivity results. Based on the lowest Landau level method, both the three-dimensional (3D) and two-dimensional (2D) scaling behaviors were observed in the fluctuation conductivity at magnetic field larger than 5 T and different temperature interval around the mean-field critical temperature Tc.