Single-bit full adder and logic gate based on synthetic antiferromagnetic bilayer skyrmions

Skyrmion-based devices are promising candidates for non-volatile memory and low-delay time computation. Many skyrmion-based devices execute operation by controlling skyrmion trajectory, which can be impeded by the skyrmion Hall effect. Here, the design of skyrmion-based arithmetic devices built on synthetic antiferromagnetic (SyAF) structures is presented, where the structure can greatly suppress skyrmion Hall effect. In this study, the operations of skyrmion-based half adder, full adder, and XOR logic gate are executed by introducing geometric notches and tilted edges, which can annihilate or diverge skyrmion. Performance of these skyrmion-based devices is evaluated, where the delay time and energy-delay product of the single-bit full adder are 1.95 ns and 2.50 × 10⁻²² Js, which are only 12% and 79% those of the previously proposed skyrmion-based single-bit full adder. This improvement is significant in the construction of ripple-carry adder and ripple-carry adder-subtractor. Therefore, our skyrmion-based SyAF arithmetic device is a promising candidate to develop high-speed spintronic devices.