Study of vortices fluctuations in deoxygenated YBaCuO single crystals

We have observed the existence of a field-independent magnetization crossin g point, M(T*), for reversible M vs. T curves obtained for several values o f field H. in three single crystals of deoxygenated YBaCuO. The crossing po ints occur in a temperature region where magnetization data obey a 2D lowes t Landau level scaling analysis, and a formulae for M(T*) obtained from 2D vortices fluctuations theory is applied. This formulae have produced confid ent values of the inter laver spacing when applied to 2D systems as Bi-base d HTS. Nevertheless, application of this formulae to experimental values of M(T*) in this work produced inconsistent values for the inter layer spacin gs of YBaCuO. (C) 2001 Elsevier Science B.V. All rights reserved.