  Newly synthesized nanostructures of graphene appear as a promising breeding
ground for new technology. Therefore, it is important to identify the role
played by the boundary conditions in their electronic features. In this
contribution we use the non-equilibrium Green's function method coupled to
tight-binding theory to calculate and compare the current patterns of hexagonal
graphene quantum dots, with contacts placed at different edge locations. Our
results reveal the formation of current vortices when the symmetry of the
contact geometry is in conflict with the symmetries of the quantum dot. The
presence of current vortices suggests the use of graphene quantum dots as
nanomagnets or magnetic nanosensors.
