Abstract
The electrical generation of orbital angular momentum in materials has attracted significant attention due to its fundamental importance and technological potential. Notably, recent experiments on orbital torque and terahertz emission suggest that Cu enables substantial charge-to-orbital interconversion upon oxidation. However, direct evidence of orbital generation in Cu remains elusive. In this work, we demonstrate current-induced orbital accumulation in pristine and naturally oxidized Cu films using magneto-optical Kerr effect measurements. We observe distinct thickness dependences of the Kerr signals in pristine and oxidized films, revealing bulk- and interface-driven orbital generation mechanisms corresponding to the orbital Hall effect and orbital Rashba-Edelstein effect, respectively. The extracted orbital diffusion length in Cu is significantly shorter than its known spin diffusion length, yet still exceeds atomic scales. These findings provide clear evidence of orbital generation in Cu and highlight the distinct bulk and interfacial mechanisms underlying it.
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The datasets generated and analyzed during the current study are available in the Figshare repository, [https://doi.org/10.6084/m9.figshare.28184159].
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Acknowledgements
KHK and GMC were financially supported by the National Research Foundation (NRF) grant funded by Korea government (RS-2025-00519398, RS-2024-00410027). DJ and PMO were financially supported by the Swedish Research Council (VR), the Knut and Alice Wallenberg Foundation (Grants No. 2022.0079 and 2023.0336), and by the Wallenberg Initiative Materials Science for Sustainability (WISE) funded by the Knut and Allice Wallenberg Foundation. This work was further supported by the EIC Pathfinder OPEN grant 101129641 “OBELIX”. The calculations were enabled by resources provided by the National Academic Infrastructure for Supercomputing in Sweden (NAISS) at NSC Linköping, partially funded by VR through Grant Agreement No. 2022-06725. HWL was financially supported by the Samsung Science and Technology Foundation (Grant No. BA-1501-51) and the National Research Foundation of Korea (NRF) (No. RS-2024-00410027).
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K.H.K. fabricated samples and performed MOKE measurements with the help of GMC. D.J. performed the theoretical calculation with the help of HWL and PMO. All authors wrote the manuscript.
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Communications Physics thanks Delin Zhang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. A peer review file is available.
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Ko, KH., Jo, D., Oppeneer, P.M. et al. Magneto-optical observation of electrically generated orbital polarization in pristine Cu and oxidized Cu. Commun Phys (2026). https://doi.org/10.1038/s42005-026-02595-7
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DOI: https://doi.org/10.1038/s42005-026-02595-7
