Effect of the magnetic-field orientation on the modulation period of the critical current of ramp-type Josephson junctions

We have investigated the dependence of the critical current I(C) on the value and orientation of an externally applied magnetic field H for interface-engineered YBa(2)Cu(3)O(7-x) ramp-type Josephson junctions. The results are compared with measurements of Nb ramp-type junctions with a PdAu interlayer. The I(C) versus H dependences are similar to Fraunhofer patterns and their modulation period changes several orders of magnitude with the orientation of the magnetic field. For both junction types, the dependence of the modulation period on the orientation of the magnetic field can be well described by the change of the relevant projection of the junction area and the influence of flux-focusing. Therefore the features of the I(C)(H) curves have to be attributed to the ramp geometry and not to specific properties of the superconducting material. (C) 2001 American Institute of Physics.