Study of vortices fluctuations in deoxygenated YBaCuO single crystals

We have observed the existence of a field-independent magnetization crossing point, M( T*), for reversible M vs. T curves obtained for several values of field H, in three single crystals of deoxygenated YBaCuO. The crossing points occur in a temperature region where magnetization data obey a 2D lowest Landau level scaling analysis, and a formulae for M( T*) obtained from 2D vortices fluctuations theory is applied. This formulae have produced confident values of the inter layer spacing when applied to 2D systems as Bi-based HTS. Nevertheless, application of this formulae to experimental values of M( T*) in this work produced inconsistent values for the inter layer spacing s of YBaCuO.