Well-defined zigzag-shaped ramp-type Josephson junctions between YBa2Cu3O7 and Nb have been studied. The magnetic field dependencies of the critical currents provide evidence for d-wave¿induced alternations in the direction of the Josephson current between neighboring sides of the zigzag structure. The arrays present controllable model systems to study the influences of ¿ facets in high-angle high- Tc grain boundaries. From the characteristics, we estimate a possible imaginary s-wave admixture to the order parameter of the YBa2Cu3O7 to be below 1%.
Smilde, H. J. H., Ariando, A., Blank, D. H. A., Gerritsma, G. J., Hilgenkamp, J. W. M., & Rogalla, H. (2002). d-Wave-Induced Josephson current counterflow in YBa2Cu3O7/Nb Zigzag Junctions. Physical review letters, 88(5), 057004-1-057004-4. https://doi.org/10.1103/PhysRevLett.88.057004