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Applied Physics Letters / Volume 84 / Issue 9 / MAGNETISM AND SUPERCONDUCTIVITY

Appl. Phys. Lett. 84, 1525 (2004); http://dx.doi.org/10.1063/1.1655692 (3 pages)

Nanotube magnetism

Y. C. Sui, R. Skomski, K. D. Sorge, and D. J. Sellmyer

Department of Physics and Astronomy and Center for Materials Research and Analysis, University of Nebraska, Lincoln, Nebraska 68588

(Received 20 October 2003; accepted 6 January 2004)

FePt and Fe3O4 nanotubes are produced by hydrogen reduction in nanochannels of porous alumina templates and investigated by electron microscopy, x-ray diffraction analysis, and magnetic measurements. Loading the templates with a Fe chloride and Pt chloride mixture followed by hydrogen reduction at 560 °C leads to the formation of ferromagnetic FePt nanotubes in the alumina pores. Using a Fe nitrate solution, thermally decomposed at 250 °C and reduced in hydrogen for 2.5 h at the same temperature, yields Fe3O4 tubes. The length of the nanotubes is about 50 μm and their diameters range from about 150 to 220 nm, depending on the thickness of the template film and the pore diameter distribution. Reflecting the different magnetocrystalline anisotropies of the compounds, the coercivities range from 0.61 kOe for Fe3O4 to 20.9 kOe for FePt. The hysteresis is explained in terms of a tubular random-anisotropy model, which yields a diameter and anisotropy dependent transition from a curling-type mode (Fe3O4) to a localized mode (FePt). © 2004 American Institute of Physics.

© 2004 American Institute of Physics

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KEYWORDS and PACS

Keywords

iron alloys, platinum alloys, iron compounds, nanotubes, ferromagnetic materials, materials preparation, magnetic anisotropy, pyrolysis, coercive force, X-ray diffraction, electron microscopy, surface magnetism

PACS

  • 75.50.Bb

    Fe and its alloys

  • 75.50.Dd

    Nonmetallic ferromagnetic materials

  • 61.46.-w

    Structure of nanoscale materials

  • 75.50.Tt

    Fine-particle systems; nanocrystalline materials

  • 81.05.Cy

    Elemental semiconductors

  • 75.30.Gw

    Magnetic anisotropy

  • 82.30.Lp

    Decomposition reactions (pyrolysis, dissociation, and fragmentation)

  • 75.70.Rf

    Surface magnetism

  • 75.60.Ej

    Magnetization curves, hysteresis, Barkhausen and related effects

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.1655692

PUBLICATION DATA

ISSN

0003-6951 (print)  
1077-3118 (online)

Publisher

$abstract.society.value is a Member of CrossRef American Institute of Physics

For access to fully linked references, you need to log in.
    S. Khizroev, M. H. Kryder, D. Litvinov, and D. A. Thompson, Appl. Phys. Lett. 81, 2256 (2002)APPLAB000081000012002256000001.

    Y. H. Huang, H. Okumura, G. C. Hadjipanayis, and D. Weller, J. Appl. Phys. 91, 6869 (2002)JAPIAU000091000010006869000001.

    R. P. Cowburn, D. K. Koltsov, A. O. Adeyeye, M. E. Welland, and D. M. Tricher, Phys. Rev. Lett. 83, 1042 (1999).


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