Nonlocal transport in twisted double bilayer graphene

In the spectrum of 2D materials, superlattices have emerged as a promising platform to modulate band structure. In graphene, it does the job of breaking the inversion symmetry between the K and K' points. In the case of bilayer graphene, spatial inversion symmetry can also be broken by applying a transverse electric field, which opens up a gap at CNP. Both these ways result in the generation of a valley current via the valley Hall effect. This shows up as non-local resistance, away from the path of charge current.
We integrate both these ways of valley current generation and implement it on dual gated twisted double bilayer graphene device, where the two copies of bilayer graphene have been rotated by 1.18^o. We observe large non-local resistance few microns away from local probes. We further demonstrate its tunability with electric field and with charge density.
One can thus explore this additional valley degree of freedom to transmit information coherently over distances of few microns in graphene. This may open up new avenues in the emerging field of valleytronics.