Advanced Materials

Template-based Synthesis and Magnetic Properties of Cobalt Nanotube Arrays

Authors

  • Dongdong Li,

    1. Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (USA)
    2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)
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  • Richard S. Thompson,

    1. Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (USA)
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  • Gerd Bergmann,

    1. Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (USA)
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  • Jia G. Lu

    Corresponding author
    1. Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (USA)
    • Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (USA).
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  • The authors wish to thank Profs. Hans Bozler, Shih-ying Hsu, Chuanhai Jiang, and Mr. Zuwei Liu for their helpful discussions and technical assistance. The work is supported by NSF grant DMR 0742225. Dongdong Li is also grateful for the support of the China Scholarship Council and the International Scientific Collaboration Fund of Shanghai. Author contributions in sequence are 35, 25, 15, and 25 percent.

Abstract

Cobalt nanotube arrays embedded in AAO templates are synthesized by direct electrodeposition with low current density. The nanotubes exhibit an hcp structure with the easy axis perpendicular to the tube. MFM imaging shows only a weak magnetic signal and SQUID measurements reveal sheared hysteresis for the field parallel to the tube axis. Combined with theoretical modeling, we confirm that the magnetization curls circumferentially around the tube wall in small external fields.

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