Easy-to-configure zero-dimensional valley-chiral modes in a graphene point junction

The valley degree of freedom in 2D materials can be manipulated for
low-dissipation quantum electronics called valleytronics. At the boundary
between two regions of bilayer graphene with different atomic or
electrostatic configurations, a valley-polarized current has been
realized. However, the demanding fabrication and operation requirements
limit device reproducibility and scalability toward more advanced
valleytronics circuits. We demonstrate a new device architecture of a
point junction where a valley-chiral 0D PN junction is easily configured,
switchable, and capable of carrying valley current with an estimated
polarization of ~80%. This work provides a new building block in
manipulating valley quantum numbers and scalable valleytronics.