DocumentCode :
964448
Title :
The shape, energy, eddy current loss, and relaxation damping of magnetic domain walls in glassy iron wire
Author :
Bishop, John E L
Author_Institution :
University of Sheffield, Sheffield, England
Volume :
13
Issue :
5
fYear :
1977
fDate :
9/1/1977 12:00:00 AM
Firstpage :
1638
Lastpage :
1645
Abstract :
A magnetostatic model is developed for extended domain boundaries of the type observed by O\´Handley [1] separating opposed axially magnetized sections of glassy iron wire. The domains in any circular wire cross section are separated by a boundary that has the minimum length consistent with their areas, and the distribution of polarization over the wire length is such as to minimize the sum of the domain wall and magnetic divergence energies. The dependence of boundary length 2L on the wire diameter 2a , remanent polarization JR, and domain wall energy per unit area γ, is evaluated so that γ may be obtained from measured values of a, L , and JR. For the glassy iron material [1] γ = 0.76 mJm-2. Eddy current loss and relaxation damping coefficients are calculated for a two-dimensional model with the same cross section and then appropriately averaged to obtain the mean coefficients for the three-dimensional model. It is shown that 55 percent of the losses observed by O\´Handley are due to eddy currents, and attribution of the remainder to relaxation damping yields a value of 6.2 kgm-2s-1for the relaxation damping coefficient indicating a Gilbert damping coefficient \\alpha _{G}\\simeq 0.06 if one assumes the exchange constant A = 10^{-11} Jm-1. De Blois\´ observations of domain wall motion in iron whiskers [9] are also briefly discussed.
Keywords :
Amorphous magnetic materials/devices; Eddy current losses; Magnetic domains; Damping; Eddy currents; Iron; Magnetic domain walls; Magnetic domains; Magnetic separation; Magnetostatics; Polarization; Shape; Wire;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/TMAG.1977.1059649
Filename :
1059649
Link To Document :
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