On the Josephson Coupling between a disk of one superconductor and a surrounding superconducting film of a different symmetry

摘要

A cylindrical Josephson junction with a spatially dependent Josephsoncoupling which averages to zero is studied in order to model the physics of adisk of d-wave superconductor embedded in a superconducting film of a differentsymmetry. It is found that the system always introduces Josepshon vortices inorder to gain energy at the junction. The critical current is calculated. It isargued that a recent experiment claimed to provide evidence for s-wavesuperconductivity in $YBa_2Cu_3O_7$ may also be consistent with d-wavesuperconductivity. Figures available from the author on request.