Dimensional crossover in the fluctuation magnetization in YBa_2Cu_3O_{7-x}and its evolution with the content of oxygen

TL;DR

This study investigates how the dimensional crossover in fluctuation magnetization of YBa2Cu3O7-x superconductors varies with oxygen content, revealing a transition from 3D to 2D behavior near the critical temperature.

Contribution

It provides experimental evidence of the evolution of the 3D-2D crossover field with oxygen doping, aligning with theoretical models and estimating anisotropy ratios.

Findings

Lower field curves follow 3D scaling laws.

Higher field curves follow 2D scaling laws.

The crossover field H_cross varies with oxygen content, matching theoretical predictions.

Abstract

We have studied the field-induced dimensional crossover in the fluctuation magnetization of three single crystals of $YBa_2Cu_3O_{7-x}$, with superconducting transition temperatures, $T_c$= 62.5, 52, and 41 K. The dimensional crossover is observed by studying the diamagnetic vortex fluctuations of the lowest-Landau-level type which occur in isochamps magnetization curves, $MvsT$, for temperatures close to the transition temperature $T_{c}(H)$. The study was accomplished by obtaining isochamps magnetization curves as a function of temperature for fields in the range of 0.4 T to 5 T. Magnetization curves for each sample when plotted together show two distinct well resolved crossing points, one formed by low field curves and located at a higher temperature than the other formed by high field curves. A lowest-Landau-level scaling analysis is applied to the curves forming the crossing points and it is verified that lower field curves obey the three-dimensional form of this scaling while the higher field curves obey the two-dimensional form. The results allow to observe the evolution of the dimensional crossover field $H_{cross}$, 3D-2D, with the content of oxygen in $YBa_2Cu_3O_{7-x}$. It is observed that the evolution of the field $H_{cross}$ with the content of oxygen in each sample qualitatively agrees with theoretical predictions and allow us to estimate the ratio of the anisotropy among the studied samples. \\pacs{74.40.+k}