Cascadable direct current driven skyrmion logic inverter gate

Nanoscale skyrmions enable ultralow-power nonvolatile logic gate designs due to their current-driven motion and topological protection. A key building block in skyrmion-based digital spintronics is the logic inverter (NOT) gate. Despite recent computational and practical demonstrations, a skyrmion-based low-power, wideband, and cascadable inverter gate is still a long way off. For skyrmion-based logic circuits, a systematic design and analysis of an inverter gate is essential. Here we present a skyrmion logic inverter design and analyze its full operation using micromagnetic modeling. Because of the substrate thermal conductivity, our investigations reveal that the all-metallic inverter gate can function with direct current drive, wide bandwidth, submicron footprint, no or low external magnetic field, cascadability, and with room-temperature thermal stability despite Joule heating. Using magnetic insulators for eliminating Joule heating and lowering the exchange stiffness, magnetic moment and other factors might further assist in reducing power consumption by more than four orders of magnitude.