Orbitronics in Zero-dimensional Graphene Nanoflakes via Electrode Coupling

Abstract

We show that graphene nanoflakes realize a previously unexplored form of orbitronics in which orbital currents emerge in the absence of intrinsic angular momentum of the constituent atoms. Starting with a hexagonal graphene nanoflake, we demonstrate the presence of energy-degenerate eigenstates with opposite non-zero expectation values of the angular momentum. Placing electrodes in an appropriate configuration on the flake couples the reservoirs more strongly to one of the two opposite-angular-momentum states, yielding a chiral current that carries a net orbital angular momentum. The resulting circulating orbital currents generate magnetic fringe fields that are experimentally accessible with spin centers or superconducting quantum interference magnetometers, providing avenues for their experimental realization. Finally, our work establishes a new platform for exploring and studying orbitronics in zero-dimensional systems.