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Phys. Rev. Lett. 93, 087204 (2004) [4 pages]

Permanent Magnetism, Magnetic Anisotropy, and Hysteresis of Thiol-Capped Gold Nanoparticles

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P. Crespo1, R. Litrán2, T. C. Rojas2, M. Multigner1, J. M. de la Fuente3, J. C. Sánchez-López2, M. A. García1, A. Hernando1, S. Penadés3, and A. Fernández2,*
1Instituto de Magnetismo Aplicado (RENFE-UCM-CSIC), P.O. Box 155, 28230 Las Rozas, Madrid, Spain and Departamento de Física de Materiales, Universidad Complutense, Madrid, Spain
2Instituto de Ciencia de Materiales de Sevilla CSIC-USE, Américo Vespucio nr.49, 41092 Sevilla, Spain and Departamento de Quimica Inorgánica, Universidad de Sevilla, Spain
3Grupo Carbohidratos, Laboratory of Glyconanotechnology IIQ-CSIC, Américo Vespucio nr.49, 41092 Sevilla, Spain

See Also: Erratum

Received 13 March 2004; published 20 August 2004

We report on the experimental observation of magnetic hysteresis up to room temperature in thiol-capped Au nanoparticles with 1.4 nm size. The coercive field ranges from 860 Oe at 5 K to 250 Oe at 300 K. It is estimated that the Au atoms exhibit a magnetic moment of μ=0.036μB. However, Au nanoparticles with similar size but stabilized by means of a surfactant, i.e., weak interaction between protective molecules and Au surface atoms, are diamagnetic, as bulk Au samples are. The apparent ferromagnetism is consequently associated with 5d localized holes generated through Au-S bonds. These holes give rise to localized magnetic moments that are frozen in due to the combination of the high spin-orbit coupling (1.5 eV) of gold and the symmetry reduction associated with two types of bonding: Au-Au and Au-S.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.93.087204
DOI:
10.1103/PhysRevLett.93.087204
PACS:
75.75.+a, 73.22.–f, 75.30.Kz, 81.07.–b

*Corresponding author.

Electronic address: asuncion@icmse.csic.es

See Also

Erratum: P. Crespo, R. Litrán, T. C. Rojas, M. Multigner, J. M. de la Fuente, J. C. Sánchez-López, M. A. García, A. Hernando, S. Penadés, and A. Fernández, Erratum: Permanent Magnetism, Magnetic Anisotropy, and Hysteresis of Thiol-Capped Gold Nanoparticles [Phys. Rev. Lett. 93, 087204 (2004)], Phys. Rev. Lett. 94, 049903 (2005).

 
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