A systematic comparison of transport properties and pinning potentials in YBCO and BiSCCO thin films

c-axis oriented single crystalline YBa2Cu3O7-x and Bi2Sr2Ca2Cu3O10 thin films were patterned for transport measurements to determine the critical current density Jc ab(H,T.?). Film to film variations of Jc were compared for a large number of YBCO samples to assess the dominant influence on the magnitude of Jc and possible correlations with the film growth conditions. A comparison of J incgq YBCO and Bi-2223 demonstrates the fundamental differences in their flux line lattice, especially at high temperatures

Critical currents and irreversibility lines in Tl-based high temperature superconductors

Various compounds (Tl-2223, Tl-1223, TI-2212) as well as material forms (single crystals, thin films, ceramics, tapes) of TI-based high temperature superconductors were investigated by magnetic and transport techniques. The Tl-2223 material has a very low lying irreversibility line (H||c) and negligible critical current densities Jc at 77 K. However, the irreversibility line is shifted to higher fields and temperatures, and Jc is strongly enhanced even at 77 K, after fast neutron irradiation. In contrast, the related Tl-1223 compound has a much steeper irreversibility line (H||c) similar to the one of Y-123. Jc is significant up to 77 K, even in the unirradiated state. Transport measurements made on Tl-1223 tapes still show much lower critical current densities. Tl-2212 and Tl-2223 thin films have Jc values at 77 K, which are comparable to those of the Tl-1223 single crystal.</p