Superconducting Pair Correlations in an Amorphous Insulating Nanohoneycomb Film

The Cooper pairing mechanism that binds single electrons to form pairs in metals allows electrons to circumvent the exclusion principle and condense into a single superconducting or zero-resistance state. We present results from an amorphous bismuth film system patterned with a nanohoneycomb array of holes, which undergoes a thickness-tuned insulator-superconductor transition. The insulating films exhibit activated resistances and magnetoresistance oscillations dictated by the superconducting flux quantum h /2 e . This 2 e period is direct evidence indicating that Cooper pairing is also responsible for electrically insulating behavior.