Critical-current measurements in planar Josephson junctions

The properties of planar high-temperature superconducting Josephson junctions are not entirely consistent with low Tc models. Some of these disparities may be intrinsic, related to the unusual superconducting properties of the electrodes, while others are due to the nonstandard planar geometry. By comparing experimental measurements of a 24 degree bicrystal substrate Josephson junction with a simple model of nonuniform current flow in a planar geometry, we show that several unusual properties can be explained as extrinsic. We show that nonuniform current feed in a planar geometry leads to a reduced critical current, an unchanged Meissner field Hco, and a power-law dependence of the critical current on Hco different from that expected in an overlap geometry. copyright 1997 American Institute of Physics