Identifying the superconducting pairing state of high-Tc oxides by the Josephson effect

The Josephson junction consisting of high-Tc superconductor, normal metal, and high-Tc superconductor is studied microscopically using the quasiclassical theory. For a d-wave pairing state and certain crystal orientations of the two superconductors, the main Shapino step is found at V=hν/4e and the diffraction pattern has the form Imax(Φ)=Ic|sin(2πΦ/Φ0)/(2πΦ/Φ0)|. The experimental verification of this property can be used to distinguish unambiguously the possible d-wave pairing state in the high-Tc superconductors from the conventional s-wave or extended s-wave pairing states. Our result is also discussed in comparison with those obtained from other types of Josephson junctions