Experimental observation of two-dimensional fluctuation magnetization in the vicinity of T_c for low values of the magnetic field in deoxygenated YBa_2Cu_3O_{7-x}

TL;DR

This study investigates the fluctuation magnetization near the critical temperature in deoxygenated YBa2Cu3O7-x, revealing a transition from 3D to 2D behavior at low magnetic fields through scaling analysis.

Contribution

It provides experimental evidence of two-dimensional fluctuation behavior in YBa2Cu3O7-x near T_c at low magnetic fields, challenging the conventional 3D-xy model.

Findings

Lower field data for T_c=41.5 K crystal collapse with 2D scaling law.

Scaling analysis with $ u$=1 indicates 2D behavior at low fields.

Data obey the lowest-Landau-level approximation for 2D fluctuations.

Abstract

We measured isofield magnetization curves as a function of temperature in two single crystal of deoxygenated YBaCuO with T_c = 52 and 41.5 K. Isofield MvsT were obtained for fields running from 0.05 to 4 kOe. The reversible region of the magnetization curves was analyzed in terms of a scaling proposed by Prange, but searching for the best exponent $\upsilon$. The scaling analysis carried out for each data sample set with $\upsilon$=0.669, which corresponds to the 3D-xy exponent, did not produced a collapsing of curves when applied to MvsT curves data obtained for the lowest fields. The resulting analysis for the Y123 crystal with T_c = 41.5 K, shows that lower field curves collapse over the entire reversible region following the Prange's scaling with $\upsilon$=1, suggesting a two-dimensional behavior. It is shown that the same data obeying the Prange's scaling with $\upsilon$=1 for crystal with T_c = 41.5 K, as well low field data for crystal with $T_c$ = 52 K, obey the known two-dimensional scaling law obtained in the lowest-Landau-level approximation.