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

Spin-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 ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mover><mml:mi>N</mml:mi> <mml:mo>⃗</mml:mo></mml:mover> <mml:annotation>$\vec N$</mml:annotation></mml:semantics> </mml:math> ). This <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mover><mml:mi>N</mml:mi> <mml:mo>⃗</mml:mo></mml:mover> <mml:annotation>$\vec N$</mml:annotation></mml:semantics> </mml:math> 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.