Self-field effects in two-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 /spl lambda//sub /spl perp//, 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.<<ETX>>