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arXiv · 2404.13405

Orbital Hall effect assisted field-free perpendicular magnetization switching

Zelalem Abebe Bekele·Yuan-Yuan Jiang·Kun Lei·Xiukai Lan·Xiangyu Liu·Hui Wen·Ding-Fu Shao·Kaiyou Wang
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Abstract

Spin-orbit torques (SOTs) generated through the conventional spin Hall effect (SHE) and/or Rashba-Edelstein effect offer potential for magnetization manipulation. However, deterministic switching of perpendicular ferromagnets via SOTs requires a strong symmetry-breaking perturbation, typically an external magnetic field. Here, we demonstrate that field-free SOT switching of perpendicular magnetization can be facilitated with the assistance of the orbital Hall effect (OHE). Using a representative Co/PtGd bilayer SOT device, we find that while the planar Hall effect (PHE) generates a finite out-of-plane damping-like torque, representing a lateral symmetry breaking, the SHE-induced torque achievable at practical current density is insufficient to switch the perpendicular magnetization. Incorporating a Mo underlayer and exploiting its strong OHE can amplify the in-plane damping-like torque via orbital-to-spin conversion, enabling efficient field-free deterministic switching without complex device geometries or low symmetric spin sources, providing a straightforward and scalable strategy for achieving high-speed and low-power spintronics.

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Zelalem Abebe Bekele, Yuan-Yuan Jiang, Kun Lei, Xiukai Lan, Xiangyu Liu, Hui Wen, Ding-Fu Shao, Kaiyou Wang. 2024-04-20. Orbital Hall effect assisted field-free perpendicular magnetization switching. https://arxiv.org/abs/2404.13405

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