Abstract
Spin-polarized light-emitting diodes convert electron spin into circularly polarized light, enabling direct optical readout of spin information and applications in on-chip information processing. Previous demonstrations have largely relied on GaAs-based emitters integrated with spin injectors. These devices, however, require complex epitaxial growth, limiting integration, while high circular polarization remains difficult, demanding high-quality materials for efficient spin injection, coherent spin transport, and spin-conserving radiative recombination. Here, we report an alternative approach for spin-polarized light-emitting diodes by employing monolayer CrI₃ as the emitter, sandwiched between two graphene/hexagonal boron nitride tunneling contacts. Although these contacts inject unpolarized carriers into CrI₃, the resulting electroluminescence exhibits circular polarization, with helicity governed by the magnetic order of CrI₃. Notably, the electroluminescence degree of polarization reaches 20% and its helicity can be reversed with a low magnetic field (~0.17 T). Combined with the inherent integrability of heterostructures, this approach provides a promising platform for future on-chip spin-optoelectronics.
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Acknowledgements
C.-H.L. acknowledges support from the National Tsing Hua University (114Q2708E1) and the National Science and Technology Council (NSTC 114-2628-M-007 −002, 113-2223-E-007-008-MY3).
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C.-H.L. conceived the experiments and supervised the project. C.-C.L. and L.-W.C. fabricated the vdW heterostructures, assisted by P.-L.C. C.K. and K.-H.P. C.-C.L. and L.-W.C. performed the measurements, assisted by W.-Q.L. and C.-H.L. Y.-J.L. provided numerical simulations. All authors contributed to the discussion of the data in the manuscript and Supplementary Information.
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Nature Communications thanks Yunqiu Kelly Luo, who co-reviewed with Thow Min Cham; Thow Min Cham 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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Lu, CC., Chang, LW., Li, WQ. et al. Spin-polarized light-emitting diodes based on CrI₃ operating without external spin injection. Nat Commun (2026). https://doi.org/10.1038/s41467-026-71743-y
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DOI: https://doi.org/10.1038/s41467-026-71743-y
