Macroscopic-ranged proximity effect in graphite

Abstract

We report proximity-induced superconducting features over macroscopic lengths in highly oriented pyrolytic graphite. The phenomenon is triggered when electrical currents are injected in the material through superconducting electrodes, few millimeters apart from each other. Such a large range is anomalous, as proximity-induced features in normal conductors hardly surpass few micrometers. The results can be explained as due to the presence of pre-existing superconductivity in graphite on small, localized regions.