Enhanced Field‐Like Torque Generated from the Anisotropic Spin‐Split Effect in Triple‐Domain RuO2 for Energy‐Efficient Spin–Orbit Torque Magnetic Random‐Access Memory

• DOI: 10.1002/advs.202413165
• Publication Date: 2025-03-12T06:38:01Z
• Authors: Thi Van Anh Nguyen; Hiroshi Naganuma; Thi Ngoc Huyen Vu; Samik DuttaGupta; Yoshiaki Saito; Duong Vu; Yasushi Endo; Shoji Ikeda; Tetsuo Endoh

AbstractSpin‐current generation via the anisotropic spin‐split effect has been predicted in antiferromagnetic RuO2, where the symmetry of RuO2 plays a critical role in spin–orbit torque (SOT). This phenomenon has garnered attention for its potential to enable energy‐efficient spintronic devices, such as SOT magnetic random‐access memory. In this study, a high‐quality RuO2 (100) epitaxial film with a well‐controlled triple‐domain‐structure is analyzed, and it is confirmed that out‐of‐plane spin‐current generation is independent of the Néel vector (). This independence of the out‐of‐plane spin current leads to equal SOT values for the two orthogonal currents. The spin‐split effect‐induced SOT demonstrates a field‐like (FL) torque efficiency (−0.066 ± 0.001) that is six times higher than that of the Slonczewski‐like torque efficiency (−0.011 ± 0.001). Furthermore, micromagnetic simulations show that this high FL torque reduces the critical switching voltage by a factor of 2.6 in the sub‐nanosecond regime in an SOT device. These findings contribute to advancing research and the development of highly energy‐efficient antiferromagnetic‐based SOT magnetic random‐access memory.