Electronic transport in clean graphene bilayer-boron nitride van der Waals heterostructure weak links

Orateur : Romain DANNEAU (INT, KIT, Karlsruhe)

We present the study of a high quality bilayer graphene connected by superconducting electrodes and sandwiched between two hexagonal boron nitride layers used as atomically flat substrate and gate dielectric. We show that this system does not remain superconducting around the charge neutrality point while a large critical current-normal resistance product is observed at high density. The presence of anomalous clear subgap features in the differential resistance which cannot be explained by the presence of multiple Andreev reflection is observed at every gate range. We show that both normal state resistance and supercurrent can be tuned by the displacement field created by the top and back gate.

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