  The proximity effect is a central feature of superconducting junctions as it
underlies many important applications in devices and can be exploited in the
design of new systems with novel quantum functionality. Recently, exotic
proximity effects have been observed in various systems, such as
superconductor-metallic nanowires and graphene-superconductor structures.
However, it is still not clear how superconducting order propagates spatially
in a heterogeneous superconductor system. Here we report intriguing influences
of junction geometry on the proximity effect for a 2D heterogeneous
superconductor system comprised of 2D superconducting islands on top of a
surface metal. Depending on the local geometry, the superconducting gap induced
in the surface metal region can either be confined to the boundary of the
superconductor, in which the gap decays within a short distance (~ 15 nm), or
can be observed nearly uniformly over a distance of many coherence lengths due
to non-local proximity effects.
