Realizing all-spin-based logic operations atom by atom.

An ultimate goal of spintronic research is the realization of concepts for atomic-scale all-spin-based devices. We combined bottom-up atomic fabrication with spin-resolved scanning tunneling microscopy to construct and read out atomic-scale model systems performing logic operations. Our concept uses substrate-mediated indirect exchange coupling to achieve logical interconnection between individual atomic spins. Combined with spin frustration, this concept enables various logical operations between inputs, such as NOT and OR.