Skyrmion-Based Racetrack Memory With Continuous Loop Built From Ferromagnetic Metal and Insulator

We propose a racetrack memory (RM) with a continuous loop structure built from a nanowire comprising a ferromagnetic insulator (FI) and a ferromagnetic metal (FM) junction. We demonstrate via micromagnetic simulations that a magnetic domain formed in the FM moves and transits through the FI due to spin-transfer torque arising from a spin-polarized current flowing in the FM. In the simulations, we employ a magnetic skyrmion (SK) domain as the magnetic domain. When the diameter of the SK is greater than the length of the FI, the SK passes through the FI. In the case of smaller SKs or a longer FI, a longer time is required for the SK to pass through the FI. We believe that our findings can significantly contribute to the further development of RMs.