Transition properties of YBa_2Cu_3O_7 step-edge Josephson junctions with various step orientations

摘要

We have studied transition properties of YBa_2Cu_3O_7 step-edge junctions with different step orientations ranging from 0 degree to 165 degrees with respect to one of the major axes of substrate at 15-degree interval. The junctions were prepared on SrTiO_3 (100) substrates by pulsed laser deposition and argon ion milling with photoresist mask. We investigated current-voltage characteristics and critical current of the junctions as a function of the angle. the junction critical current showed an angle dependent modulation with maxima near 0 or 90 degree and minima near 45 and 135 degrees. We believe that the critical current variation with the step orientation is associated with the symmetry of high Tc superconductor.