Presentation Information
[10p-PB3-28]Demonstration of bit-shifting in vertical domain wall motion memory
〇(D)Dongchan Jeong1, Feifan Ye1, Yoichi Shiota1,2, Hisakazu Matuski1,2, Ryusuke Hisatomi1,2, Shutaro Karube1,2, Satoshi Sugimoto3, Shinya Kasai3, Teruo Ono1,2,4 (1.ICR, Kyoto Univ., 2.CSRN, Kyoto Univ., 3.NIMS, 4.SRIS, Tohoku Univ.)
Keywords:
Magnetic memory
Domain wall motion memory offers fast and energy-efficient data manipulation, making it a promising candidate for next-generation non-volatile storage. Motivated by these advantages, we propose a vertical multi-bit architecture to realize ultra-high-density memory arrays [1]. In this structure, spin–orbit torque (SOT) is utilized for switching the magnetization of the bottom magnetic layer, while spin–transfer torque (STT) is responsible for shifting the written bits toward the upper magnetic layers. In our previous study, simulations revealed that the vertical structure exhibits both low operating current densities (<1011A·m-2) and high thermal stability [2], and the feasibility of data writing and shifting in such a configuration was experimentally demonstrated in a 2-bit memory device [3].
In this presentation, we show the results of controllable data shifting by STT in a 4-bit memory device. Multilayers of Ta (5)/Pt (10)/Co (1.2)/Cu (3)/Co (0.5)/Pt (0.4)/Co (0.5)/Cu (3)/Co (0.5)/Pt (0.4)/Co (0.5)/Cu (3)/Co (0.5)/Pt (0.4)/Co (0.5)/Cu (3)/Pt (3) (unit: nm) on Si-SiO2 substrate were deposited by magnetron sputtering. Electron-beam lithography was used to pattern pillars device with diameters of 100, 200, and 300 nm and subsequently etched by ion milling system. The magnetization configurations were measured by giant magnetoresistance (GMR) and the anomalous Hall resistance. We observed changes of GMR and anomalous Hall resistance in SOT switching experiments and bit-shift experiments. Our results indicate that current-induced methods enable the implementation of multiple magnetization configurations.
References
[1] Y. M. Hung et al., Journal of the Magnetics Society of Japan 45, 6 (2021).
[2] Y. M. Hung et al., Applied Physics Express 14, 023001 (2021).
[3] F. Ye et al., IEEE Transactions on Magnetics 61, 3401004 (2025).
In this presentation, we show the results of controllable data shifting by STT in a 4-bit memory device. Multilayers of Ta (5)/Pt (10)/Co (1.2)/Cu (3)/Co (0.5)/Pt (0.4)/Co (0.5)/Cu (3)/Co (0.5)/Pt (0.4)/Co (0.5)/Cu (3)/Co (0.5)/Pt (0.4)/Co (0.5)/Cu (3)/Pt (3) (unit: nm) on Si-SiO2 substrate were deposited by magnetron sputtering. Electron-beam lithography was used to pattern pillars device with diameters of 100, 200, and 300 nm and subsequently etched by ion milling system. The magnetization configurations were measured by giant magnetoresistance (GMR) and the anomalous Hall resistance. We observed changes of GMR and anomalous Hall resistance in SOT switching experiments and bit-shift experiments. Our results indicate that current-induced methods enable the implementation of multiple magnetization configurations.
References
[1] Y. M. Hung et al., Journal of the Magnetics Society of Japan 45, 6 (2021).
[2] Y. M. Hung et al., Applied Physics Express 14, 023001 (2021).
[3] F. Ye et al., IEEE Transactions on Magnetics 61, 3401004 (2025).