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A note on Ferromagnetism

Published online by Cambridge University Press:  24 October 2008

R. H. Fowler
Affiliation:
Trinity College
F. C. Powell
Affiliation:
Gonville and Caius College.

Extract

The purpose of this note is to amplify the discussion and conclusions of a recent paper by one of us. It has recently been shown by Webster, drawing largely from the work of Weiss and Forrer, that in single crystals of both iron and nickel there is a family of natural directions of micromagnetization defined by the observed directions of easy holomagnetization. The evidence presented by Webster is completely convincing, and we therefore may refine our picture of micromagnetization by asserting that the micro-elements are all (holo)magnetized in one or other of the directions of easy holomagnetization. These directions are the family of six directions (± 1, 0, 0) (0, ± 1, 0) (0, 0, ± 1) for iron and the family of eight directions (± 1, ± 1, ± 1) for nickel. We wish to comment on Webster's theory later in connection with the properties of cobalt.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1931

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References

* Powell, , Proc. Roy. Soc. A, vol. 130, p. 167 (1930).CrossRefGoogle Scholar

Webster, , Proc. Phys. Soc. London, vol. 42, p. 431 (1930).CrossRefGoogle Scholar

Weiss, and Forrer, , Ann. de Physique, vol. 5, p. 153 (1926).CrossRefGoogle Scholar

§ It seems to us convenient to standardize some such terms to discriminate between the natural state of zero bulk magnetization of a ferromagnetic below the Curie point when micro-elements must still be magnetized to saturation (micro-magnetized state), and the state of magnetization in bulk when the magnetism of the micro-elements has been aligned (holomagnetized state).

* Akulov, , Zeit. f. Physik, vol. 57, p. 249 (1929).CrossRefGoogle Scholar

Powell, loc. cit.

* (l, m, n) must equal (1, 0, 0) also if (X, Y, Z) = (1, 1, 0).

* Kaya, , Science Reports, Tôhoku University (1928), p. 1157.Google Scholar

* There is a misprint in Powell, loc. cit., where the first equation of § 5 should obviously read

or what is the equivalent,

* The values given in Powell, loc. cit., for Fe and Ni are not quite correct for the data used to determine them. The correct values are

See a forthcoming discussion of magnetostriction by Powell.