Nature 413, 716–718 (2001)
In this Letter we reported high-temperature ferromagnetism in a polymeric phase of pure carbon that was purportedly free of ferromagnetic impurities1. Since then, however, measurements made on the same and similar samples using particle-induced X-ray emission (PIXE) with a proton microbeam have indicated that these had considerable iron content2,3,4. Also, polymerized C60 samples mixed with iron before polymerization had a similar Curie temperature (500 K) to those we described1, owing to the presence of the compound Fe3C (cementite)5. In addition, it has since been shown that the pure rhombohedral C60 phase is not ferromagnetic6.
Nevertheless, magnetic order in impurity-free graphitic structures at room temperature has been demonstrated independently7 (before and after publication of ref. 1). Ferromagnetic properties may yet be found in polymerized states of C60 with different structural defects and light-element (H, O, B, N) content8.
T.L.M. and P.S. decline to sign this retraction because they do not believe that the earlier results1, supported in subsequent studies9,10, are totally invalidated by these findings2,3,4,5,6.
Makarova, T. L. et al. Magnetic carbon. Nature 413, 716–718 (2001); corrigendum 436, 1200 (2005).
Höhne, R. & Esquinazi, P. Can carbon be ferromagnetic? Adv. Mater. 14, 753–756 (2002)
Spemann, D. et al. Evidence for intrinsic weak ferromagnetism in a C60 polymer by PIXE and MFM. Nucl. Instrum. Meth. B 210, 531–536 (2003)
Han, K. H. et al. Observation of intrinsic magnetic domains in C60 polymer. Carbon 41, 785–795 (2003); addendum 431, 2425–2426 (2003)
Talyzin, A., Dzwilewski, A., Drubovinsky, L., Setzer, A. & Esquinazi, P. Magnetic properties of polymerized C60 with Fe. Preprint at http://arXiv.org/abs/cond-mat/0602306
Boukhvalov, D. W. et al. Testing the magnetism of polymerized fullerene. Phys. Rev. B 69, 115425 (2004)
Makarova, T. & Palacio, F. (eds) Ch. 24 Carbon-based Magnetism (Elsevier, Amsterdam, 2006)
Makarova, T. L. et al. Magnetism in photopolymerized fullerenes. Carbon 41, 1575–1584 (2003)
Narozhnyi, V. N. et al. Ferromagnetic carbon with enhanced Curie temperature. Physica B 329, 1217–1218 (2003)
Wood, R. A. et al. Ferromagnetic fullerene. J. Phys. Condens. Matter 14, L385–L391 (2002)
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