Demagnetizing Factor

demagnetizing factor

[dē′mag·nə‚tīz·iŋ ‚fak·tər]
(electromagnetism)
The ratio of the negative of the demagnetizing field to the magnetization of a sample. Also known as demagnetization coefficient.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Demagnetizing Factor

 

When a specimen or device component of open shape, such as a cylinder, made of a ferromagnetic material is magnetized by an applied field, magnetic poles are formed at the opposite ends of the specimen. These poles cause within the specimen a magnetic field opposite in direction to the applied field. The demagnetizing field Hs of the poles of the specimen is proportional to the specimen’s magnetization J: Hs = NJ. The coefficient N, which is called the demagnetizing factor, is thus equal to the ratio of the strength of the specimen’s demagnetizing field and the specimen’s magnetization. If the specimen is located in an applied magnetic field of strength Ha, then the true strength of the field in the specimen is equal to Ht = HaNJ.

The demagnetizing factor can be calculated precisely only for ellipsoids of revolution, which have uniform magnetization. For a sphere, N = ⅓, for a very thin plate, N = 1; and for an infinitely long cylinder in a transverse field, N = ½. For some specimens of simple shape, the demagnetizing factor is calculated by empirical formulas, but in most cases it is determined experimentally.

REFERENCE

Kifer, I. I. lspytaniia ferromagnitnykh materialov, 3rd ed. Moscow, 1969.

I. I. KIFER

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Sanchez, "Radial magnetometric demagnetizing factor of thin disks," IEEE Transactions on Magnetics, vol.
Sanchez, "Fluxmetric and magnetometric demagnetizing factors for cylinders," Journal of Magnetism and Magnetic Materials, vol.
The topics include the dependence of granular matrix demagnetizing factor on the matrix relative size, water-resistant material from fiber and acrylc emulsion terpolymer, measuring the thermo-radiation characteristics of infrared window materials, comparing optical and scintillation images obtained by using a fiber-optic beta/gamma imaging detector, and a dual-sequenced real coded genetic algorithm for picking process optimization.
That is, in essence, the saturation field [H.sub.sat] = 4[pi][M.sub.s] x [N.sub.zz], [N.sub.zz] the demagnetizing factor [26], when domain structure is suppressed and sample is under saturation.
Schrefl et al., "Grain-size dependent demagnetizing factors in permanent magnets," Journal of Applied Physics, vol.
[3] Osborn JA (1945) Demagnetizing Factors of the General Ellipsoid.
[4] Chen DX, Brug JA, Goldfarb RB (1991) Demagnetizing Factors for Cylinders.
The relationships for [H.sub.i] are shape-related and are the result of demagnetizing factors that are given by Kittel's equation.[1] Resonance absorption occurs when the electrons spinning the stationary field [H.sub.i] at a frequency given by Equation 1.