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Magnetic edge states and coherent manipulation of graphene nanoribbons

Nature volume 557, pages 691–695 (2018)Cite this article

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A Publisher Correction to this article was published on 26 June 2018

This article has been updated

Abstract

Graphene, a single-layer network of carbon atoms, has outstanding electrical and mechanical properties1. Graphene ribbons with nanometre-scale widths2,3 (nanoribbons) should exhibit half-metallicity4 and quantum confinement. Magnetic edges in graphene nanoribbons5,6 have been studied extensively from a theoretical standpoint because their coherent manipulation would be a milestone for spintronic7 and quantum computing devices8. However, experimental investigations have been hampered because nanoribbon edges cannot be produced with atomic precision and the graphene terminations that have been proposed are chemically unstable9. Here we address both of these problems, by using molecular graphene nanoribbons functionalized with stable spin-bearing radical groups. We observe the predicted delocalized magnetic edge states and test theoretical models of the spin dynamics and spin–environment interactions. Comparison with a non-graphitized reference material enables us to clearly identify the characteristic behaviour of the radical-functionalized graphene nanoribbons. We quantify the parameters of spin–orbit coupling, define the interaction patterns and determine the spin decoherence channels. Even without any optimization, the spin coherence time is in the range of microseconds at room temperature, and we perform quantum inversion operations between edge and radical spins. Our approach provides a way of testing the theory of magnetism in graphene nanoribbons experimentally. The coherence times that we observe open up encouraging prospects for the use of magnetic nanoribbons in quantum spintronic devices.

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Fig. 1: Functionalized graphene nanoribbons.
Fig. 2: Static spectra and magnetic interaction pathways.
Fig. 3: Spin–lattice relaxation and spin coherence times.
Fig. 4: Hyperfine coupling and multi-spin operability in GNRs.

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Change history

  • 26 June 2018

    In Fig. 1 of this Letter, there should have been two nitrogen (N) atoms at the 1,3-positions of all the blue chemical structures (next to the oxygen atoms), rather than one at the 2-position. The figure has been corrected online, and the original incorrect figure is shown as Supplementary Information to the accompanying Amendment.

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Acknowledgements

We thank the European Research Council (ERC-StG 338258 OptoQMol), the EU (COST-CA15128, MOLESCO-606728 and Graphene Flagship), the EPSRC (QuEEN grant), the Royal Society (University Research Fellowship and URF grant), the RFBR (17-53-50043), the Max Planck Society and the German DAAD Bilateral Exchange of Academics (2015/50015739) for financial support.

Reviewer information

Nature thanks E. Coronado, D. Gatteschi, A.-P. Li and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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Authors and Affiliations

  1. Department of Materials, University of Oxford, Oxford, UK

    Michael Slota & Lapo Bogani

  2. Centre for Advanced ESR, University of Oxford, Oxford, UK

    Michael Slota, William K. Myers, Arzhang Ardavan & Lapo Bogani

  3. Max-Planck-Institut für Polymerforschung, Mainz, Germany

    Ashok Keerthi, Martin Baumgarten, Akimitsu Narita & Klaus Müllen

  4. N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk, Russia

    Evgeny Tretyakov

  5. Clarendon Laboratory, University of Oxford, Oxford, UK

    Arzhang Ardavan

  6. Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, UK

    Hatef Sadeghi & Colin J. Lambert

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Contributions

M.S. and W.K.M. performed the ESR characterization. A.K. and E.T. performed the synthesis and related characterization, for which M.B., A.N. and K.M. provided supervision. H.S. and C.J.L. performed the numerical modelling. M.S., W.K.M., A.A. and L.B. contributed to the ESR data analysis. M.S., A.N., K.M. and L.B. conceived the experiments and M.S. and L.B. wrote the manuscript. All authors contributed to the discussion and to the final version of the manuscript.

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Correspondence to Lapo Bogani.

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The authors declare no competing interests.

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Supplementary Information

Supplementary Information

This file contains Supplementary Text and Data, Supplementary Figures 1-15, Supplementary Tables 1-3 and a Supplementary Bibliography.

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Slota, M., Keerthi, A., Myers, W.K. et al. Magnetic edge states and coherent manipulation of graphene nanoribbons. Nature 557, 691–695 (2018). https://doi.org/10.1038/s41586-018-0154-7

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