Ion‐Modulated All‑Van Der Waals Spin–Orbit Torque Magnetic Tunnel Junctions With Multilevel Switching
Yuxin Tian, Zhiyan Jia, Qian Chen, Shizhe Wu, Mengfan Zhao, Yi Wang, Xueqi Guo, Xinyu Gao, Yonghao Sun, Yan Zhang, Fang Zhang, Kun Ye, Shuai Hu, Haixin Chang, Jingsheng Chen, Yong JiangABSTRACT
Advancing van der Waals (vdW) spintronics requires hardware for multistate storage and in‐memory processing. All‑vdW spin–orbit torque magnetic tunnel junctions (SOT‑MTJs) that simultaneously achieve field‑free operation and multilevel switching have remained elusive. Here, we report an ion‑modulated all‑vdW SOT‑MTJ with a stack structure of WTe 2 /Fe 3 GaTe 2 /WSe 2 /Fe 3 GaTe 2 /CuInP 2 S 6 (CIPS). We then apply pulsed currents along the crystallographic a ‑axis of WTe 2 , which produce field‑free deterministic SOT switching with ultralow critical current density of 2–5 × 10 6 A/cm 2 at 300 K, and excite resistance changes at the MTJ. The SOT efficiency of WTe 2 is ∼0.35. The CIPS ion modulator enables localized Cu + migration and accumulation at the interface under a lateral electric field, thereby destroying the perpendicular magnetic anisotropy of the adjacent reference layer and inducing an intermediate resistance state in the MTJ. These ion‐modulated devices exhibit tunneling magnetoresistance ranging from 0.2% to 5%. This work addresses the integration challenges of all‑vdW SOT‑MTJs and demonstrates multilevel switching controlled by a solid‑state ion source in this architecture, generating three distinct nonvolatile resistance levels that serve as ternary connection weights in a neural network for image recognition. These results establish a scalable platform for low‐current switching, multilevel storage, and image recognition, promising energy‐efficient in‐memory computing.