Room‐Temperature Anomalous Hall Effect and Out‐of‐Plane Spin–Orbit Torques in CoFe 2 O 4 ‐Buffered RuO 2

Abstract

Realizing room‐temperature out‐of‐plane spin currents remains a key challenge for low‐power perpendicular spin–orbit torque devices. Oxides with strong spin–orbit coupling are highly desirable spin sources for spintronic applications, and RuO 2 has recently attracted widespread attention owing to its excellent spin transport properties. However, the generation of out‐of‐plane spin polarization is limited to specific crystallographic orientations, restricting materials design flexibility and practical device integration. Here, we demonstrate that interfacial magnetic coupling between RuO 2 and an insulating ferromagnet can provide an effective route to circumvent this constraint. In RuO 2 (110)/CoFe 2 O 4 heterostructures, the interfacial coupling induces a net magnetization component in RuO 2 tilted toward the film plane, giving rise to a robust anomalous Hall effect up to room temperature. Spin‐torque ferromagnetic resonance measurements reveal a high spin–orbit torque efficiency of ∼0.18 in CoFe 2 O 4 ‐buffered RuO 2 , representing a sixfold enhancement compared with bare RuO 2 (110) films. Notably, the spin tilting of RuO 2 generates a distinct z‐polarized spin‐current component with a torque efficiency of ∼0.014, indicating that interfacial magnetic engineering enables out‐of‐plane spin polarization in RuO 2 (110). These results suggest interfacial magnetic modulation as a versatile strategy for realizing room‐temperature anomalous Hall effects and efficient spin–orbit torques in strongly spin–orbit coupled oxide heterostructures, opening new opportunities for oxide‐based spintronic applications.