Multilayer Nanomagnet Threshold Logic

Nanomagnet logic (NML) uses dipolar magnetic coupling between nanomagnets to efficiently perform nonvolatile logical operations. As the basis logic element, the three-input minority gate is the simplest threshold logic function. Recent work has explored the potential for increased logical expressivity with a nanomagnet threshold logic family that reduces area, delay, and energy costs. However, as such previous work was limited to a single layer of nanomagnets, only negative input weights could be provided, thus limiting circuit expressivity and efficiency. This article therefore, proposes multilayer nanomagnet threshold logic systems that provide both positive and negative weights by leveraging multilayer structures that produce both ferromagnetic and antiferromagnetic dipolar coupling. The availability of both positive and negative weights drastically increases logical expressivity, and the feasibility of the proposed multilayer nanomagnet threshold logic system is demonstrated through micromagnetic simulations. A single seven-input gate is shown to perform more than 86 distinct logic functions, reducing the number of gates and clock cycles required for complex logic circuits by as much as 67%.