The influence of the method of demagnetization on the reversible permeability of a high-permeability nickel-iron alloy

Jackson, R. C.; Lee, E W; Troughton, A G H

doi:10.1088/0508-3443/9/12/309

Cited by 10 publications

(2 citation statements)

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“…Measurements were first made on the specimens 'as received', that is in a thermally demagnetized state, and also after demagnetization in a progressively attenuated alternating field. While slight differences in p~ and, to a lesser extent, 7 were observed for these two conditions (as reported by Jackson et al 1958), these differences were less marked than for Complete permeability spectra for the specimens of extreme grain size 9 pni and 140 pni are plotted in figures 1 and 2 ; the behaviour of those with intermediate grain sizes ranged between these two extremes, as can be seen from the record of the analysis in table 1. In contrast to iron (11), the low-frequency behaviour of Mumetal proved to be distinctly dependent on grain size G (see figure 3).…”

Section: Measurements On Demagnetized Statessupporting

confidence: 48%

“…Phillips and Shephard (1970) have been led to this conclusion after correlating data on the temperature variation of p ~, the saturation magnetization M s and the anisotropy constant K1. Measurements at low frequencies reveal loss anomaly factors 7 considerably greater than unity in the demagnetized state (Richards et al 1957) and much higher still in polarizing fields (Troughton 1958). Parkin (1953) has reported that both p~ and 7 depend quite strongly on grain size-a fact difficult to reconcile with a predominantly rotational permeability.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic domain studies using permeability spectra III. Ni-Fe-Cu-Mo alloy

Bishop

Collar

Lee

1971

J. Phys. D: Appl. Phys.

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Measurements of the complex initial permeability of several specimens of Mumetal (77% Ni, 14% Fe, 5% Cu, 4% Mo) have been made from 0-30 MHz. The samples were polycrystalline rings 50 μm in thickness; the mean grain size ranged from 9 μm to 140 μm. The results were analysed in terms of the domain model previously employed by the authors in 1969 and 1970, yielding the following main conclusions.Despite the low anisotropy (of order 100 erg cm−3), there exists a well-defined domain structure. Except near the surface, where the domain size is independent of grain size, the scale of the domain structure is found to be nearly proportional to crystallite size to the power 0·4.Some of this domain structure persists in polarizing fields as great as 20 times the coercive field. There is no evidence for an independent contribution to the permeability from rotational processes which, it is suggested, are instead strongly coupled to wall motion. There is evidence that the behaviour is beginning to be influenced by intrinsic spin phenomena at frequencies greater than about 30 MHz.

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Section: Measurements On Demagnetized Statessupporting

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Magnetic domain studies using permeability spectra III. Ni-Fe-Cu-Mo alloy

Bishop

Collar

Lee

1971

J. Phys. D: Appl. Phys.

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Magnetic parameters of Materials

Heck¹

1974

Magnetic Materials and Their Applications

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Field‐impressed anisotropies of magnetic susceptibility and remanence in minerals

Potter¹,

Stephenson²

1990

J. Geophys. Res.

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The application of alternating (AF) or direct (DF) magnetic fields to samples containing dispersed particles of magnetite, titanomagnetite, or maghemite has been found to alter significantly the measured low‐field susceptibility anisotropy even though the particle orientation is unchanged. The acquisition of isothermal remanent magnetization (IRM) is also strongly dependent on the previous AF treatment given to the samples. A method of quantifying the changes brought about by application of the fields is described. The samples studied were intrinsically isotropic or only weakly anisotropic, and the computed impressed susceptibility or IRM ellipsoids produced by the applied fields were ellipsoids of revolution with the unique axis aligned with the applied field axis. The size and shape of the field‐impressed ellipsoids were strongly dependent upon particle size. These effects might thus form the basis of a rapid, nondestructive means of estimating particle size in rocks. The results also have important implications for magnetic fabric analysis and the static AF demagnetization of rocks. In particular, to ensure that the intrinsic magnetic fabric is measured without any field‐impressed component of anisotropy, samples should not be subjected to static AF demagnetization prior to the determination of either low field susceptibility anisotropy or IRM anisotropy. Samples should also not carry a significant remanence (such as an IRM acquired in a field greater than about 5 mT) prior to low field susceptibility anisotropy analysis.

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The influence of the method of demagnetization on the reversible permeability of a high-permeability nickel-iron alloy

Cited by 10 publications

References 1 publication

Magnetic domain studies using permeability spectra III. Ni-Fe-Cu-Mo alloy

Magnetic domain studies using permeability spectra III. Ni-Fe-Cu-Mo alloy

Magnetic parameters of Materials

Field‐impressed anisotropies of magnetic susceptibility and remanence in minerals

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