SELF-FIELD EFFECTS IN 2-DIMENSIONAL NB JOSEPHSON-JUNCTION ARRAYS

We have measured two-dimensional niobium Josephson junction arrays in which self induced fields are important. We find an increase of the depinning current when lambda(perpendicular to), the penetration depth in the array, is of the order of one. There is evidence for a destruction of commensurate vortex states in the arrays as the depinning current becomes almost independent of the applied magnetic field. Our data also show that self-field effects change the array flux-flow dynamics and decrease the effective array viscosity.