Abstract
Spin-1/2 Heisenberg antiferromagnetic chains are one-dimensional platforms that are excellent for exploring quantum magnetic states and quasiparticle fractionalization. Understanding quantum magnetism and quasiparticle excitation at the atomic scale is crucial for manipulating the quantum spin systems. Here we report the fabrication of spin-1/2 Heisenberg chains through on-surface synthesis and in situ reduction. A closed-shell nanographene is employed as a precursor for Ullmann coupling to avoid side reactions, thus obtaining oligomer chains. Following exposure to atomic hydrogen and tip manipulation, the closed-shell polymers are transformed into spin-1/2 chains with controlled lengths by reducing ketone groups and subsequent hydrogen desorption. The spin excitation gaps are found to decrease in a power law as the chain lengthens, suggesting a gapless feature in the thermodynamic limit. Interestingly, the spinon dispersion is extracted from the inelastic spectroscopic spectra, agreeing well with calculations. Our results demonstrate the great potential of fabricating desired quantum systems through a combined on-surface synthesis and reduction approach.
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Data availability
All data generated in this study are available via figshare at https://doi.org/10.6084/m9.figshare.28091300 (ref. 48).
Code availability
The relevant codes are available via GitHub at https://github.com/Suxl1994/spin_chain_ED.
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Acknowledgements
P.Y. gratefully acknowledges the financial support from the National Natural Science Foundation of China (22472098), Science and Technology Commission of Shanghai Municipality (24ZR1452100) and ShanghaiTech start-up funding. X.S. acknowledges the Postdoctoral Science Foundation of China (2021M702188). C.L. acknowledges the NSFC grant 12304230 and Postdoctoral Science Foundation of China (grant GZB20230422). Y.-F.J. acknowledges support from the National Program on Key Research Project (grant no. 2022YFA1402703). We also thank Fermion Instruments for supplying the hydrogen cracker source.
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X.S., Z.D., Y.H. and P.Y. conceived the project. X.S., Z.D. and P.Y. acquired and analysed the experimental data. N.K., C.L. and Y.-F.J. performed all the calculations. Y.H. and K.Y. designed and synthesized the molecular precursors. All the authors discussed and contributed to the paper writing.
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Nature Synthesis thanks Jiong Lu, Shiyong Wang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Peter Seavill, in collaboration with the Nature Synthesis team.
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Supplementary Figs. 1–18 and experimental details.
Supplementary Data
The source data for Supplementary Figs. 11, 15b and 17a–c.
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Source Data Fig. 1
The source data for STM and AFM images in Fig. 1.
Source Data Fig. 2
The source data for AFM images, STS and simulated spectra in Fig. 2.
Source Data Fig. 3
The source data for calculated and experimental spin excited energies of OSCs in Fig. 3.
Source Data Fig. 4
The source data for AFM images, STM images, STS, and experimental and calculated spinon dispersion in Fig. 4.
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Su, X., Ding, Z., Hong, Y. et al. Fabrication of spin-1/2 Heisenberg antiferromagnetic chains via combined on-surface synthesis and reduction for spinon detection. Nat. Synth 4, 694–701 (2025). https://doi.org/10.1038/s44160-025-00744-4
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DOI: https://doi.org/10.1038/s44160-025-00744-4
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