Measurements of the superconducting fluctuations in optimally doped BaFe_2−<i>x</i>Ni<i>_x</i>As₂under high magnetic fields: probing the 3D-anisotropic Ginzburg–Landau approach

Abstract

The superconducting fluctuations well inside the normal state of Fe-based\nsuperconductors were experimentally studied through the in-plane\nparaconductivity in several high-quality optimally-doped\nBaFe$_{2-x}$Ni$_x$As$_2$ crystals. These measurements were performed in\nmagnetic fields with amplitudes up to 14 T, and different orientations relative\nto the crystals c axis (0, 53 and 90 degrees). The results allowed a stringent\ncheck of the applicability of a recently proposed Ginzburg-Landau approach for\nthe fluctuation electrical conductivity of 3D anisotropic materials in presence\nof finite applied magnetic fields.\n