Magnetotransport properties in Hg-1201 single crystals

The in-plane (rho (ab)) and out-of-plane (rho (c)) resistivities have been determined on a nearly optimized (Hg(0.8)Cu(0.2))Ba(2)CuO(4+delta) (Hg-1201) single crystal (T(c) similar to 94 K). The obtained resistivities values, rho (ab) (300 K) = 510 mu Omega cm and rho (c) (300 K) = 0.35 Omega cm, provide a room temperature anisotropy ratio (rho (c)/rho (ab))1/2 = 26. Temperature dependencies of both resistivities show a curvature change at a same temperature, T, which suggests a pseudogap opening at this temperature. From rho (ab)(T, B) measurements under magnetic field, a positive magnetoresistivity is found, and the scaling of the fluctuations reveals that a 2D-3D crossover occurs for this cuprate. Such a dimensional change was not observed by magnetization measurements. (C) 2001 Elsevier Science B.V. All rights reserved.