Spintronics has emerged as a promising frontier in information technology, offering non-volatility, ultrafast switching, and energy-efficient operation surpassing traditional electronic memory devices. Central to this field is spin-orbit torque (SOT), a mechanism that enables the manipulation of magnetic states via charge currents in heavy metals coupled with ferromagnetic layers. However, a significant obstacle hindered the widespread adoption of SOT-based devices: the requirement of an external magnetic field to achieve deterministic magnetization switching. This limitation complicates device architectures, increases power consumption, and impedes high-density integration. Current approaches to realize field-free switching include structural asymmetries, geometric engineering, and exploiting intrinsic crystal symmetries. Although progress has been made, these methods often involve complex fabrication processes, additional circuitry, or limited scalability, posing challenges for industrial application. Achieving reliable, scalable, and energy-efficient field-free switching remains a pivotal challenge in advancing spintronic memory technologies.
Addressing these challenges, a research team from Chinese Academy of Sciences, Hebei University of Technology and Zhejiang Hikstor Technology introduced a novel mechanism based on controlled domain wall (DW) chirality. By engineering a tensile-strain-induced easy-cone magnetic anisotropy in a W/CoFeB/MgO heterostructure and performing a one-time global magnetic initialization, they achieved precise control over the DW chirality. This intrinsic chirality breaks time-reversal symmetry, enabling deterministic magnetization switching driven solely by spin-orbit torque, without any external magnetic field.
The approach was implemented on a 300 mm industrial manufacturing platform , demonstrating high-performance magnetic tunnel junctions (MTJs) with near 100% field-free switching probability, high thermal stability, endurance exceeding 10 12 cycles, and robust operation up to 350°C.
Moreover, this method simplifies device design by eliminating the need for auxiliary pinning layers or geometric asymmetries, offering a balanced combination of efficiency, reliability, and manufacturability. The sub-100 nm SOT-magnetic tunnel junctions (MTJs) were fabricated using a 28-nm node process on 300-mm wafers. A process widely used in the CMOS industry. The findings open pathways toward integrating field-free SOT-MRAM into commercial data centres, mobile, and wearable devices.
The Future: Looking ahead, the team anticipates that anisotropy engineering will become as central as torque engineering in the next generation of SOT-MRAM. Future research will focus on designing stacks with stronger magnetoelastic coupling to increase the easy-cone angle without sacrificing perpendicular retention. As junction dimensions approach the sub-20 nm regime, the researchers aim to co-optimize materials and patterning—using atomically engineered interfaces and low-damage etching—to ensure that chiral magnetic DW chirality remains programmable and reproducible at manufacturable nodes.
This magnetic DW chirality-mediated switching paradigm, enabled by a tensile-strained SOT-MTJ stack, demonstrates that manipulating internal magnetic DW chirality can effectively replace external field interventions. The devices fabricated on the 300-mm wafer line exhibit a near-unity switching probability, a thermal stability factor ( Δ ) of 64, and endurance exceeding 10 12 cycles, all while maintaining thermal resilience up to 350 °C. Furthermore, the one-time global initialization process leverages standard MRAM equipment, ensuring no additional power overhead or complex local circuitry.
The Impact: This work bridges a fundamental magnetic switching mechanism with industrial manufacturability, offering a CMOS-compatible, scalable pathway toward high-performance SOT-MRAM. By integrating materials innovation with scalable manufacturing, this magnetic DW chirality-mediated switching paradigm provides a viable solution for the growing demands of data-intensive computing.
The research has been recently published in the online edition of Materials Futures , a prominent international journal in the field of interdisciplinary materials science research.
Reference: Peiyue Yu, Meiyin Yang, Yanru Li, Shuo Xu, Ying Li, Shuaiyu Gong, Jingsong Huang, Jianfeng Gao, Weibing Liu, Shasha Wang, Lei Zhao, Enlong Liu, Wenlong Yang, Yang Gao, Shikun He, Dashan Shang, Jun Luo. Field-free spin-orbit torque switching enabled by controllable domain wall chirality[J]. Materials Futures . DOI: 10.1088/2752-5724/ae53fe
Materials Futures
Field-free spin-orbit torque switching enabled by controllable domain wall chirality
18-Mar-2026