Harnessing Rashba–Edelstein effect at Pt/DyOx interface for efficient spin–orbit torques

Abstract

Spin–orbit torque (SOT) can be enhanced through the interfacial Rashba–Edelstein effect, which arises in systems with broken inversion symmetry and converts charge current into nonequilibrium spin accumulation, thus boosting spin current. Despite its known effects, the role of 4f-electron lanthanide oxides in influencing interfacial phenomena has remained largely unexplored. In this study, we investigate the potential of f-electron lanthanide oxides, particularly at the Pt/DyOx interface, to enhance SOT. The gradient oxidation structure of the 4f-electron rare-earth oxide DyOx was confirmed through ultra-high-precision line scanning electron energy loss spectroscopy. By employing spin–torque ferromagnetic resonance, we achieve an extraordinary SOT efficiency of ξFMR = 0.758 in the Pt/DyOx heterojunction, exceeding that of pure Pt by more than a factor of ten. This enhancement reduces the critical current density required for magnetization switching to 2.25–3.48 × 106 A·cm−2, which is only 15% of the current density needed for pure Pt. Beyond improving SOT efficiency, the integration of 4f rare-earth oxides at the interface provides an advanced technical pathway for developing CMOS-compatible and energy-efficient spintronic technologies.