Domain-stored skyrmion structures for a reading error-detectable racetrack memory

Abstract

Magnetic racetrack memory (RTM) uses a series of either domains or skyrmions as data bits along nanowires. However, it lacks reading error detection capability in nanowires, which requires high electric current density for the deterministic motion of domain walls (DWs) or skyrmions. Here, we propose a method of a reading error-detectable RTM and explore domain-stored skyrmion structures for this RTM. This method uses domains as memory cells and assigns the presence and absence of a skyrmion in a domain to different bits, enabling the electrical signal of any memory cells to output the opposite sign to that of the adjacent memory cells. Using simulations and Lorentz microscopy, we demonstrate that perpendicularly magnetized nanowires with relatively large Dzyaloshinskii-Moriya interaction can achieve domain-stored skyrmion structures. Additionally, our simulations show that when DWs approach to skyrmions during spin-orbit torque-induced motion, angular momentum transfers from DWs to skyrmions, resulting in fast motion of skyrmions.