Weak Field Magnetic Susceptibility Fluctuations Above the Superconducting Transition YBa $$_{2}$$ 2 Cu $$_{3-x}$$ 3 - x Fe $$_{x}$$ x O $$_{7-\delta }$$ 7 - δ (0.05 $$\le x$$ ≤ x $$\le $$ ≤ 0.12)

Abstract

This paper reports the production of YBa $$_{2}$$ Cu $$_{3-x}$$ Fe $$_{x}$$ O $$_{7-\delta }$$ (0.05 $$\le x$$ $$\le $$ 0.12) superconducting system by using the standard solid-state reaction technique. A Rietveld refinement of the experimental X-ray diffraction patterns allows the determination of the lattice parameters and the phase composition of the studied system; the mean present phase shown is an orthorhombic phase Pmmm. Magnetic and transport properties are typical for superconducting samples. In this paper, magnetic susceptibility fluctuations are studied in the limit of weak magnetic fields. For each of the samples, the best fit of the experimental data of $$\Delta \chi $$ /T, in the limit of weak magnetic fields in function of the reduced temperature, allowed us to obtain the values of $$A_\mathrm{s}$$ (diamagnetism of Schmidt) and $$B_\mathrm{LD}$$ (LD parameter). The Lawrence–Doniach model (LD) has been used for the fluctuation analysis. It is demonstrated, by means of the analysis of the thermal fluctuations, that the YBa $$_{2}$$ Cu $$_{3-x}$$ Fe $$_{x}$$ O $$_{7-\delta }$$ system has an excellent 2D scaling behavior (BLD).