Inducing and controlling magnetism in the graphene lattice through a trapping potential*

We study strongly interacting ultracold spin-1/2 fermions in a honeycomb lattice in the presence of a harmonic trap.
We solve the model non-perturbatively by means of a inhomogeneous Dynamical Mean-Field Theory.
We tune the strength of the harmonic trap to confine the fermions in artificial structures which are reminescent of graphene nanoflakes in solid state. Starting from a non-magnetic state and increasing the strength of the harmonic potential, we are able to induce different magnetic states such as a Néel like antiferromagnetic state, ferromagnetic or ferrimagnetic states, as well as mixtures of these basic states, which can be used to design spin-filters and transistors. The realization of different magnetic patterns is associated with the terminations of the artificial structures induced in a controlled way by the confining potential. We suggest that our cold-atom-based implementation for synthesizing edges in order to create magnetism is also applicable in real materials and switchable spintronic devices.