COMPARISON OF THE SUPERCONDUCTING PAIRING BETWEEN THE OXIDE SUPERCONDUCTORS BA1-XKXBIO3 AND YBA2CU3O6.6 USING PHASE-SENSITIVE JOSEPHSON TUNNELING

We compare the Josephson tunneling of a suspected d-wave superconducto r, YBa2Cu3O6.6, with that of another oxide superconductor Ba1-xKxBiO3, For comparison the critical current I-c vs applied field of a single- crystal Josephson junction injecting supercurrent in the [110] directi on is measured for both superconductors. For the YBa2Cu3O6.6 single cr ystal (T-c=60 K), the critical current is a minimum at zero applied fi eld, while for Ba1-xKxBiO3, the critical current reveals a maximum at zero field. The results are consistent with ad-wave order parameter fo r YBa2Cu3O6.6, and conventional s-wave superconductivity for Ba1-xKxBi O3.