UPPER CRITICAL-FIELD, PENETRATION DEPTH, AND GL PARAMETER OF TL-2223 SINGLE-CRYSTALS

A Tl2Ca2Ba2Cu3O10 single crystal of platelet shape with T-c=121.5 K wa s investigated by SQUID magnetometry. Zero field cooled (=ZFC) and fie ld cooled (=FC) measurements were carried out in different fields with the applied field parallel to the crystallographic c-axis. Taking the fluctuations of the vortices in Josephson-coupled layered superconduc tors into account, the temperature dependent penetration depth lambda( ab), the Ginzburg Landau parameter kappa, and the upper critical field H-c2,, are calculated from the reversible ZFC/FC magnetization data. The H-c2-data (H parallel to c) can be fitted linearly at higher tempe ratures. The temperature dependent penetration depth does not follow t he empirical law lambda(T)=lambda(0)/(1-(T/T-c)(4))(1/2).