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

TL;DR

This study investigates superconducting fluctuations in optimally-doped BaFe$_{2-x}$Ni$_x$As$_2$ under high magnetic fields, testing the validity of a 3D anisotropic Ginzburg-Landau model for fluctuation conductivity.

Contribution

It provides experimental validation of a recent Ginzburg-Landau approach for 3D anisotropic superconductors under magnetic fields.

Findings

Superconducting fluctuations observed up to 14 T magnetic fields.

The Ginzburg-Landau model accurately describes fluctuation conductivity.

Anisotropic effects depend on magnetic field orientation.

Abstract

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