Programmable nanomagnet-logic majority gate

We build on previous work and present the first experimental demonstration of a completely programmable NML majority gate. To ensure complete programmability, each driver magnet will need to be set independently. This can be accomplished by changing magnet aspect ratio. As the length of the magnet increases along its easy axis, its coercivity in that direction increases. Thus, it will require a higher magnetic field for re-magnetization. Quantitative simulation data are shown in Fig. 3 (obtained via simulations with NIST´s OOMMF suite2). The M-H curves show increasing coercivity for 60x90x30 nm³ and 60x230x30 nm³ supermalloy magnets. One can clearly see that a higher magnetic field is needed to switch that state of the higher aspect ratio magnet. Thus, if we vary the lengths of the driver (horizontal) magnets of the majority gate shown in Fig. 1c, and any applied external field is (i) sufficient to set the state of a target driver, (ii) insufficient to switch other (longer) driver(s), and (iii) sufficient to place the other (vertical) magnets in the gate into a metastable state (per Fig. 2), then the drivers can retain their distinct initial magnetization state even after the entire gate process is complete. This has been experimentally demonstrated and we discuss results below. We have demonstrated the independent programmability of the driver magnets of the majority gate to obtain all logic variations in one physical layout. This demonstrates fully programmable logic which is especially important when considering how to use this technology at the functional unit level.