PROPERTIES OF YBA2CU3O7-DELTA YBA2COXCU3-XOY/YBA2CU3O7-DELTA JOSEPHSON EDGE JUNCTIONS WITH -LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.3 AND THE EFFECT OF FLUX-FLOW ON THEIR NORMAL RESISTANCE/

YBa2Cu3O7-delta (YBCO) based SNS edge junctions with cobalt doped YBCO barriers were prepared and characterized. At 77 K, good junctions had RSJ-like I-V curves with excess current, magnetic suppression of I(c) of about 50% or more, and clear microwave steps. The conductance valu es 1/R(N) at 77 K of junctions with different barrier thickness and co mposition, were proportional to the junction areas A, but show little correlation with the thickness of the barriers t(B) in the range of 15 less-than-or-equal-to t(B) less-than-or-equal-to 100 nm. The correspo nding I(c)R(N) products were observed to scale as J(c)0.66 +/- 0.09, s imilar to what was found by others. At the same time, the measured val ues of R(N) are much smaller than what is expected based on the dimens ions of the junction and the resistivity of the barrier material. To e xplain all of this, we propose a model in which at high supercurrent d ensities, flux flow of Josephson vortices in the junction leads to R(N ) values which are lower than expected. This model predicts R(N)(T) is -proportional-to square-root [t(B) + 2lambda(L)(T)]/J(c)(T), which fit s the observed results very well.