Electric-field controlled spin in bilayer triangular graphene quantum dots

We present theoretical results based on mean-field and exact many-body approaches showing that in bilayer triangular graphene quantum dots with zigzag edges, the magnetism can be controlled by an external vertical electric field. We demonstrate that without electric field, the spins of the two layers of the quantum dot interact ferromagnetically. At a critical value of the electric field, the total spin of the bilayer structure can be turned off or reduced to a single-localized spin, a qubit isolated from contacts and free from interaction with nuclear spins.