Measurements of the superconducting fluctuations in optimally-doped BaFe$_{2-x}$Ni$_x$As$_2$ under high magnetic fields: Probing the 3D anisotropic Ginzburg-Landau approach

摘要

The superconducting fluctuations well inside the normal state of Fe-basedsuperconductors were experimentally studied through the in-planeparaconductivity in several high-quality optimally-dopedBaFe$_{2-x}$Ni$_x$As$_2$ crystals. These measurements were performed inmagnetic fields with amplitudes up to 14 T, and different orientations relativeto the crystals c axis (0, 53 and 90 degrees). The results allowed a stringentcheck of the applicability of a recently proposed Ginzburg-Landau approach forthe fluctuation electrical conductivity of 3D anisotropic materials in presenceof finite applied magnetic fields.