CYLINDRICAL JOSEPHSON TUNNELING

Josephson-tunneling experiments between small cylindrical superconductors are proposed. The essential idea is that the wave functions in the superconductors must be of the form ψ1=|ψ|f(r)ein1θ and ψ2=|ψ|f(r)ei(n2θ+δ0) to guarantee that they are single valued. This, together with the Josephson relation J=J0sinδ, where J0 is the maximum Josephson current and δ is the phase difference between the superconductors, leads to the conclusion that the Josephson current will be zero for n1 n2. For n1=n2 the current will be proportional to f12f22 in the thin-film approximation. If the inner cylinder is solid and of higher transition temperature then J0f22 providing a means for determining the order parameter as a function of magnetic field. The ratio of cylinder radius to coherence length determines, in large measure, the variation of J0 with field. Specific examples are given. © 1979 The American Physical Society.