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arXiv · 2606.14868

Absence of orbital current torque in a magnetic metal/Pt/CuOx trilayer

Zhihao Yan·Lujun Zhu·Xiangrui Qin·Zhengxiao Li·Lijun Zhu
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Abstract

Naturally oxidized copper (CuOx) was cited as an exceptionally strong orbital-current source despite the keen debate over the concept of orbital current. Here, we report unambiguous experimental evidence for the absence of a detectable orbital-current torque in the Fe/Pt/CuOx trilayers. Using a magnetic metal detector of Fe thin film with a negligible self-induced torque, the damping-like torque due to Pt/CuOx bilayers is clarified to entirely arise from the spin Hall spin current of the Pt. As the Pt thickness increases, the torque for Fe/Pt/CuOx and Fe/Pt/MgO increases coherently and monotonically, as exactly expected from the spin Hall effect of Pt and the drift-diffusion model of spin angular momentum. These findings suggest poor generality or even universal absence of orbital current torque.

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Zhihao Yan, Lujun Zhu, Xiangrui Qin, Zhengxiao Li, Lijun Zhu. 2026-06-12. Absence of orbital current torque in a magnetic metal/Pt/CuOx trilayer. https://arxiv.org/abs/2606.14868

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