Binary memory switching in zigzag-edge graphene nanostrips

Owing to a peculiar boundary condition, the ground state of any hydrogen-terminated zigzag-edge graphene nanostrip is predicted to exhibit spin-polarized edge states. We capture this physics in a model which has a Hamiltonian that consists of tight-binding terms and terms describing the potential from a spin-dependent scalar field. The model is solved in the presence of a ballistic current passing through the nanostrip. Studying the grand canonical potential for the system, it is shown that the spin-polarized state collapses above a certain bias. Below that threshold there is a bi-stable regime which could be exploited in a possible memory device. The memory could be both set and cleared through the bias and be read by measuring the current through the device.