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arXiv · 2506.07608

Orbital Hall Effect Enables Field-Free Magnetization Reversal in Ferrimagnets without Additional Conversion Layer

Zelalem Abebe Bekele·Kun Lei·Xiukai Lan·Xiangyu Liu·Hui Wen·Weihao Li·Yongcheng Deng·Wenkai Zhu·Kaiming Cai·Kaiyou Wang
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Abstract

The spin Hall effect (SHE) enables efficient electrical manipulation of magnetization through the spin Hall current \left(\mathbit{J}_{\mathbit{SHE}}\right), advancing energy-efficient spintronics. In parallel, the orbital Hall effect (OHE) offers an alternative pathway to SHE for converting charge current into an angular momentum flow. In this study, we demonstrate field-free current-induced perpendicular ferrimagnetic deterministic switching within a Mo/CoGd device without an additional orbital-to-spin conversion layer. This is achieved by harnessing localized orbital Hall currents \left(\mathbit{J}_{\mathbit{OHE}}\right) generated in the Mo layer. The in-plane symmetry breaking at the Mo/CoGd surface-interface layer, validated by a pronounced planar Hall effect, gives rise to a substantial unconventional z-polarized damping-like torque. The CoGd serves a dual role: not only as a converter that transforms the significant \mathbit{J}_{\mathbit{OHE}} into \mathbit{J}_{\mathbit{SHE}} but also as a ferrimagnetic self-switching mechanism. This dual functionality enables highly efficient field-free current-induced magnetization switching with a critical current density as low as \mathbf{2}.\mathbf{51}\ \times{\mathbf{10}}^\mathbf{6} A cm-2. Our work highlights the potential of orbital Hall currents for energy-efficient magnetization switching, making a notable contribution to the burgeoning field of orbitronics.

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Zelalem Abebe Bekele, Kun Lei, Xiukai Lan, Xiangyu Liu, Hui Wen, Weihao Li, Yongcheng Deng, Wenkai Zhu, Kaiming Cai, Kaiyou Wang. 2025-06-09. Orbital Hall Effect Enables Field-Free Magnetization Reversal in Ferrimagnets without Additional Conversion Layer. https://arxiv.org/abs/2506.07608

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