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Journal of Magnetism and Magnetic Materials 297 (2006) 5459 Magnetization of cobalt nanodiscs

Summary: Journal of Magnetism and Magnetic Materials 297 (2006) 5459
Magnetization of cobalt nanodiscs
J. Waddella
, S. Inderheesa
, M.C. Aronsona,, S.B. Dierkera,b
Department of Physics, University of Michigan, 500 East University Avenue, Ann Arbor, MI 48109-1120, USA
National Synchrotron Light Source, Brookhaven National Laboratory, Upton, NY 11973-5000, USA
Received 17 November 2004; received in revised form 7 February 2005
Available online 17 March 2005
We have studied the magnetization and AC susceptibility of a dilute colloidal dispersion of -Co nanodiscs. The
temperature dependence of the magnetization implies that the nanodisc moments become largely static below a
blocking temperature which exceeds room temperature. The related anisotropy energy is significantly larger than the
magnetocrystalline anisotropy for bulk -Co, which may result either from surface modifications to the crystalline
anisotropy, or perhaps from shape anisotropy. The saturation moment is found to be temperature independent, over a
wide range of temperatures and also close to the blocking temperature, although the field at which saturation occurs
varies considerably with temperature. A coercive field of 1700 Oe is found at low temperature, indicating that
magnetization reversal involves the coordinated rotation of the moments in individual nanodiscs. Aging effects are


Source: Aronson, Meigan - Department of Physics and Astronomy, SUNY at Stony Brook


Collections: Materials Science; Physics