High-field transport in bilayer graphene-hBN superlattices

By applying strong in-plane electric fields in the superlattice formed by aligning the crystallographic axes of Bernal bilayer graphene (BBG) and hexagonal boron nitride (hBN), we experimentally access a critical regime where transport is dominated by inter-band tunnelling. We reveal a regime of instabilities dominated by Barkhausen-like noise, suggesting high-field domain formation pinned by crystallographic defects. In addition, using out-of-plane displacement field to narrow the bandwidth, we bring the high-field system to the vicinity of a van Hove singularity, where a bistability with a giant photoresponse emerges.