Intrinsic weak link originating from tilt in contacts between d_x2-y2 wave superconductors

It is shown that a boundary region with a depressed order parameter is intrinsically created at the interface between two dx2-y2 wave superconductors, which form a contact at a tilt angle. The contact is a weak link or a Josephson junction, with properties determined by the misalignment angle. Complementing existing theories that discuss the influence of dx2-y2 symmetry on the charge transfer across junctions, the ideas presented provide insights into the origin of the junction formed in such configurations. The mechanism discussed is of relevance for the understanding of the electronic properties of grain boundaries in superconductors, including the angular dependence of the critical current density.