Letter | Published:

Spin-half paramagnetism in graphene induced by point defects

Nature Physics volume 8, pages 199202 (2012) | Download Citation

Abstract

The possibility to induce a magnetic response in graphene by the introduction of defects has been generating much interest, as this would expand the already impressive list of its special properties and allow novel devices where charge and spin manipulation could be combined. So far there have been many theoretical studies (for reviews, see refs 1, 2, 3) predicting that point defects in graphene should carry magnetic moments μμB and these can in principle couple (anti)ferromagnetically1,2,3,4,5,6,7,8,9,10,11,12. However, experimental evidence for such magnetism remains both scarce and controversial13,14,15,16. Here we show that point defects in graphene—(1) fluorine adatoms in concentrations x gradually increasing to stoichiometric fluorographene CFx=1.0 (ref.  17) and (2) irradiation defects (vacancies)—carry magnetic moments with spin 1/2. Both types of defect lead to notable paramagnetism but no magnetic ordering could be detected down to liquid helium temperatures. The induced paramagnetism dominates graphene’s low-temperature magnetic properties, despite the fact that the maximum response we could achieve was limited to one moment per approximately 1,000 carbon atoms. This limitation is explained by clustering of adatoms and, for the case of vacancies, by the loss of graphene’s structural stability. Our work clarifies the controversial issue of graphene’s magnetism and sets limits for other graphitic compounds.

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Acknowledgements

This work was supported by the UK Engineering and Physical Sciences Research Council and by the Academy of Finland.

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Affiliations

  1. Manchester Centre for Mesoscience and Nanotechnology, Manchester M13 9PL, UK

    • R. R. Nair
    • , M. Sepioni
    • , I-Ling Tsai
    • , T. Thomson
    • , A. K. Geim
    •  & I. V. Grigorieva
  2. Department of Physics, University of Helsinki, PO Box 43, FI-00014, Finland

    • O. Lehtinen
    • , J. Keinonen
    •  & A. V. Krasheninnikov
  3. Department of Applied Physics, Aalto University, PO Box 11100, FI-00076, Finland

    • A. V. Krasheninnikov

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Contributions

I.V.G. and A.K.G. devised the project, analysed the results and wrote the paper. I.V.G. supervised the experiments. R.R.N. carried out measurements and analysis of fluorinated graphene. M.S. and I-L.T. carried out magnetization measurements of ion-irradiated graphene. M.S. carried out measurements of HOPG. O.L., J.K. and A.V.K. carried out ion irradiations and analysis of defect structures. All authors contributed to discussions.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to I. V. Grigorieva.

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DOI

https://doi.org/10.1038/nphys2183

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