Three-dimensional anisotropic fluctuation diamagnetism around the superconducting transition of Ba(1-x)KxFe2As2 single crystals in the finite-field (or Prange) regime

TL;DR

This study investigates the anisotropic fluctuation diamagnetism in Ba(1-x)KxFe2As2 single crystals near the superconducting transition, extending previous work into the finite-field regime and confirming the applicability of the 3D anisotropic Ginzburg-Landau theory.

Contribution

It extends fluctuation diamagnetism measurements into the finite-field regime and validates the 3D anisotropic Ginzburg-Landau model with a total-energy cutoff for these superconductors.

Findings

Fluctuation diamagnetism is strongly field-dependent near the transition.

The 3D anisotropic Ginzburg-Landau model accurately describes the data.

The total-energy cutoff improves the theoretical description.

Abstract

The magnetization around the superconducting transition was recently measured in a high-quality Ba(1-x)KxFe2As2 single crystal with magnetic fields applied along and transverse to the crystal Fe-layers [J. Mosqueira et al., Phys. Rev. B 83, 094519 (2011)]. Here we extend this study to the finite field (or Prange) regime, in which the magnetic susceptibility is expected to be strongly dependent on the applied magnetic field. These measurements are analyzed in the framework of the three-dimensional anisotropic Ginzburg Landau (3D-aGL) approach generalized to the short wavelength regime through the introduction of a total-energy cutoff in the fluctuation spectrum. The results further confirm the adequacy of GL approaches to describe the fluctuation effects close to the superconducting transition of these materials.