The c-axis transport properties of a high-pressure synthesized PrFeAsO0.7 single crystal are studied using s-shaped junctions. Resistivity anisotropy of about 120 detected at 50 K shows the presence of strong anisotropy in the electronic states. The obtained critical current density for the c-axis of 2.9*10^5 A/cm^2 is two orders of magnitude larger than that in Bi2Sr1.6La0.4CuO6+d. The appearance of a hysteresis in the current-voltage curve below T_c is the manifestation of the intrinsic Josephson effect similar to that in cuprate superconductors. The suppression of the critical current-normal resistance (I_cR_n) product is explained by an inspecular transport in s_pm-wave pair potential.Comment: 8 pages, 2 figure

The specific capacitance Cs of Nb/AlOx/Nb Josephson tunnel junction has been measured by means of the superconducting quantum interference device (SQUID) resonance technique. We have investigated the junctions with critical current densities Jc in the range of 0.1–18 kA/cm2 and found that 1/Cs linearly depends on a logarithm of Jc. This suggests that the barrier thickness is moderately uniform in the junction area and increases continuously during growth. The results also show that increasing Jc reduces time constants of the junction.

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Abstract-Dual-rail logic circuit elements based on rapid single-flux-quantum (RSFQ) technology have been designed and simulated.The proposed circuits can operate asynchronously, since dual-rail data include timing information in themselves. Therefore dual-rail logic scheme has a possibility of solving some problems of RSFQ circuits with flow clocking, which would become more serious as operating speed and complexity of the circuit increase.Implementation of RSFQ dual-rail AND and XOR cells is described. A scheme of transferring data from a serial flow-clocked circuit to a parallel dual-rail circuit is also proposed, which uses a fully asynchronous dual-rail demultiplexer.