Dependence of the Josephson coupling of unconventional superconductors on the properties of the tunneling barrier

The Josephson coupling between a conventional and an unconventional superconductor is investigated as a function of the properties of the tunneling barrier. A simple model is adopted for the tunneling probability and it is shown that its variation dramatically affects the ${\mathit{I}}_{\mathit{c}}$ ${\mathit{R}}_{\mathit{n}}$ product of an s-d, as opposed to an s-s junction. Based on these conclusions, experiments are proposed to probe the symmetry of the order parameter in high-temperature superconductors.