Li Shen, Lin Xiaoyang, Li Pingzhi, Zhao Suteng, Si Zhizhong, Wei Guodong, Koopmans Bert, Lavrijsen Reinoud, Zhao Weisheng
School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China.
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
ACS Appl Mater Interfaces. 2023 Aug 23;15(33):39946-39955. doi: 10.1021/acsami.3c06447. Epub 2023 Aug 15.
Magnetic racetrack memory has significantly evolved and developed since its first experimental verification and is considered one of the most promising candidates for future high-density on-chip solid-state memory. However, both the lack of a fast and precise magnetic domain wall (DW) shifting mechanism and the required extremely high DW motion (DWM) driving current make the racetrack difficult to commercialize. Here, we propose a method for coherent DWM that is free from the above issues, which is driven by chirality switching (CS) and an ultralow spin-orbit-torque (SOT) current. The CS, as the driving force of DWM, is achieved by the sign change of the Dzyaloshinskii-Moriya interaction, which is further induced by a ferroelectric switching voltage. The SOT is used to break the symmetry when the magnetic moment is rotated in the Bloch direction. We numerically investigate the underlying principle and the effect of key parameters on the DWM by micromagnetic simulations. Under the CS mechanism, a fast (∼10 m/s), ultralow energy (∼5 attoJoule), and precisely discretized DWM can be achieved. Considering that skyrmions with topological protection and smaller size are also promising for future racetracks, we similarly evaluate the feasibility of applying such a CS mechanism to a skyrmion. However, we find that the CS causes it to "breathe" instead of moving. Our results demonstrate that the CS strategy is suitable for future DW racetrack memory with ultralow power consumption and discretized DWM.
自首次实验验证以来，磁赛道存储器有了显著的发展，被认为是未来高密度片上固态存储器最有前途的候选者之一。然而，缺乏快速精确的磁畴壁（DW）移动机制以及所需的极高的DW运动（DWM）驱动电流使得赛道存储器难以商业化。在此，我们提出一种用于相干DWM的方法，该方法不存在上述问题，由手性切换（CS）和超低自旋轨道扭矩（SOT）电流驱动。CS作为DWM的驱动力，通过Dzyaloshinskii-Moriya相互作用的符号变化实现，而这种变化由铁电切换电压进一步诱导。当磁矩在布洛赫方向旋转时，SOT用于打破对称性。我们通过微磁模拟对DWM的基本原理和关键参数的影响进行了数值研究。在CS机制下，可以实现快速（约10米/秒）、超低能量（约5阿托焦耳）且精确离散化的DWM。考虑到具有拓扑保护且尺寸更小的斯格明子对未来的赛道存储器也很有前景，我们同样评估了将这种CS机制应用于斯格明子的可行性。然而，我们发现CS会使其“呼吸”而非移动。我们的结果表明，CS策略适用于未来具有超低功耗和离散化DWM的DW赛道存储器。
