Complementary Skyrmion Racetrack Memory Enables Voltage-Controlled Local Data Update Functionality

Magnetic skyrmion (Sk), instead of magnetic domain wall (DW), holds great promise as alternative information carriers in the future ultradense and low-power racetrack memory (RM). More importantly, by exploiting its unique properties, such as particle-like behavior and topological stability, Sk enables new functionalities that may be inaccessible to DW in RM applications. In this paper, we propose a complementary Sk-RM structure that enables voltage-controlled local data update functionality. Similar to our previous design in addressing the data representation issue, data information is represented in a robust way that both '0' and '1' are represented in the form of Sks and are moved synchronously by the spin Hall effect. Furthermore, this complementary Sk-RM structure can be developed for enabling local data update functionality, because Sks can be shifted between the two nanotracks by regulating the voltage-controlled gates. In this case, data bits '0' and '1' can be converted to each other freely within the nanotrack without being moved out of the nanotrack. This functionality brings great benefits in data access and management. Functionality and performance of the proposed design are studied with micromagnetic simulations.