ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The phenomenological model of magnetization kinetics developed by Estrin et al. [J. Phys. 1, 4845 (1989)] yields a macroscopic magnetic equation of state or magnetic constitutive equation of functional form μ0H=f(Jirr,J(overdot)irr), where, μ0H is the internal magnetic field, Jirr is the irreversible magnetic polarization and J(overdot)irr its time derivative. In differential form the relation takes the form μ0 dH=(1/χirr)dJirr+Λd(ln J(overdot)irr). The quantity Λ is related to the activation volume involved in the process of irreversible magnetization. To obtain Λ, three different experimental techniques are used. One involves the traversal of hysteresis loops at constant J(overdot)irr, from which both χirr and Λ can be obtained most directly, using a modified version of a technique previously described. The second method involves traversing the hysteresis loop at constant μ0H(overdot), and subsequently separating the reversible and irreversible components of magnetization. In the third method, the parameter Λ is obtained from magnetic viscosity measurements, which is the technique most commonly used. Results are presented for all three experimental techniques for measurements performed on Alnico-type permanent magnets. The limitations of each method will be reviewed in relation to materials properties.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.355713
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