Vortex state in ferromagnetic nanoparticles
Citation:
Betto, D., Coey, J.M.D., Vortex state in ferromagnetic nanoparticles, Journal of Applied Physics, 115, 17, 2014, 17D138-Download Item:

Abstract:
The evolution of the magnetic state of a soft ferromagnetic nanoparticle with its size is usually thought to be from superparamagnetic single domain to blocked single domain to a blocked multidomain structure. Néel pointed out that a vortex configuration produces practically no stray field at the cost of an increase in the exchange energy, of the order of , where JS 2 is the bond energy, R is the particle radius, and c is of the order of the exchange length. A vortex structure is energetically cheaper than single domain when the radius is greater than a certain value. The correct sequence should include a vortex configuration between the single domain and the multidomain states. The critical size is calculated for spherical particles of four important materials (nickel, magnetite, permalloy, and iron) both numerically and analytically. A vortex state is favored in materials with high magnetisation.
Sponsor
Grant Number
Science Foundation Ireland (SFI)
10/IN1.13006
Author's Homepage:
http://people.tcd.ie/jcoeyDescription:
PUBLISHED
Author: COEY, JOHN
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Journal ArticleCollections:
Series/Report no:
Journal of Applied Physics115
17
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Full text availableKeywords:
soft ferromagnetic nanoparticleDOI:
http://dx.doi.org/10.1063/1.4867597Licences: