Abstract
Open-shell nanographenes exhibit unconventional π-magnetism arising from topological frustration or strong electron–electron interaction. However, conventional design approaches are typically limited to a single magnetic origin, which can restrict the number of correlated spins or the type of magnetic ordering in open-shell nanographenes. Here we present a design strategy that combines topological frustration and electron–electron interactions to fabricate a large fully fused ‘butterfly’-shaped tetraradical nanographene on Au(111). We employ bond-resolved scanning tunnelling microscopy and spin-excitation spectroscopy to resolve the molecular backbone and reveal the strongly correlated open-shell character, respectively. This nanographene contains four unpaired electrons with both ferromagnetic and anti-ferromagnetic interactions, harbouring a many-body singlet ground state and strong multi-spin entanglement, which is well described by many-body calculations. Furthermore, we study the magnetic properties and spin states in the nanographene using a nickelocene magnetic probe. The ability to imprint and characterize many-body strongly correlated spins in polyradical nanographenes paves the way for future advancements in quantum information technologies.
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Data availability
All data are available in the manuscript or the supplementary information. The SPM, spectra data and theoretical calculation results are available in the Zenodo repository at https://doi.org/10.5281/zenodo.8365320.
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Acknowledgements
J. Lu acknowledges the support from Ministry of Education (MOE) grants (MOE T2EP50121-0008, MOE-T2EP10221-0005 and MOE-T2EP10123-0004), and National Research Foundation (NRF), Prime Minister’s Office, Singapore, under the Competitive Research Program Award (NRF-CRP29-2022-0004), Agency for Science, Technology and Research (A*STAR) under its Advanced Manufacturing and Engineering Individual Research Grants (AME IRG) grant (project 715 no. M21K2c0113). This work was supported by Science and Technology Project of Jiangsu Province, grant number BZ2022056. We acknowledge support from the CzechNanoLab Research Infrastructure supported by MEYS CR (LM2023051) and the Grant Agency of Czech Republic (GACR) project no. 23-05486 S. J.W. acknowledges the financial support from an A*STAR AME IRG grant (A20E5c0089) and NRF Investigatorship award (NRF-NRFI05-2019-0005). S.S. acknowledges the support from A*STAR under its AME Young Individual Research Grants (YIRG) grant (M22K3c0094). This work was supported by the Czech Ministry of Education, Youth and Sports from the Large Infrastructures for Research, Experimental Development and Innovations project ‘IT4 Innovations National Supercomputing Center–LM2015070’, and the Computational Chemical Sciences Program of the US Department of Energy, Office of Science, Basic Energy Science (BES), Chemical Sciences, Geosciences and Biosciences Division in the Center for Scalable and Predictive methods for Excitations and Correlated phenomena (SPEC) at Pacific Northwest National Laboratory (PNNL).
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J. Lu supervised the project. S.S., J.W. and J. Lu. conceived and designed the experiments. L.V. and P.J. conceived the theoretical studies. S.S., H.Y. and M.T. performed the on-surface synthesis and LT–STM measurements. A.P.S., O.S. and P.J. performed the IETS measurements with NiCp2 tip. G.L. and J.W. performed the organic synthesis of the precursor. A.M., L.V., D.S., M.K., Q.C., S.E., J.B. and P.J. performed the theoretical calculations. J. Li helped with the data presentation. S.S., P.J. and J. Lu. wrote the manuscript with input from all authors. All authors contributed to the scientific discussion.
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Song, S., Pinar Solé, A., Matěj, A. et al. Highly entangled polyradical nanographene with coexisting strong correlation and topological frustration. Nat. Chem. (2024). https://doi.org/10.1038/s41557-024-01453-9
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DOI: https://doi.org/10.1038/s41557-024-01453-9