Geometry-dependent conductance oscillations in graphene quantum dots

Utilizing rectangular graphene quantum dots with zigzag horizontal boundaries as a paradigm, we find that the conductance of the dots can exhibit significant oscillations with the position of the leads. The oscillation patterns are a result of quantum interference determined by the band structure of the underlying graphene nanoribbon. In particular, the power spectrum of the conductance variation concentrates on a selective set of bands of the ribbon. The computational results are substantiated by a heuristic theory that provides selection rules for the concentration on the specific dispersion bands.