Characterization of submicrometer ferromagnetic NOT gates

Abstract

We present operation phase diagrams of all-metallic submicrometer ferromagnetic NOT–gate devices. The phase diagrams summarize four different types of behavior, in which devices can operate correctly with either one or three domain walls propagating through them, nucleate domain walls, or pin a domain wall, leading to its annihilation with a succeeding domain wall. We use these phase diagrams to investigate the influence of junction dimensions on domain wall nucleation and pinning, and determine optimized junction parameters for NOT–gate operation. Furthermore, we demonstrate how changing the NOT–gate orientation to an applied field affects the operating phase diagram and may assist the integration of NOT-gates with other types of junction in the near future to realize a full magnetic logic scheme. By fabricating the NOT–gate junctions within a magnetic feedback loop, the direction of domain wall propagation is shown to be reversible and the input and output wires therefore interchangeable.