We study the critical current I c dependence on applied magnetic field H for multifacet YBa 2Cu 3O 7-δ/Au/Nb ramp-type zigzag Josephson junctions. For many experiments, one would like to apply a homogeneous field in the junction plane. However, even tiny misalignments can cause drastic deviations from homogeneity. We show this explicitly by measuring and analyzing I c versus H for an eight-facet junction, forming an array of 4×(0-π) segments. The ramp angle is θ r=8. H is applied under different angles θ relative to the substrate plane and different angles φ relative to the in-plane orientation of the zigzags. We find that a homogeneous flux distribution is only achieved for an angle θ h1-2 and that even a small misalignment ∼0.1 relative to θ h can cause a substantial inhomogeneity of the flux density inside the junction, drastically altering its I c versus H interference pattern. We also show that there is a dead angle θd* relative to θ h of similar magnitude, where the average flux density completely vanishes.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 24 Oct 2012|