PHYSICS

W. F. BROWN, Jr.

ON THE THEORY OF MAGNETOSTRICTION OF NICKEL SINGLE CRYSTALS

(Presented by Academician L. A. Artsimovich, December 14, 1956)

Recently Akulov ($^1$) compared his ($^2$) theory of the change in longitudinal elongation in nickel crystals upon magnetization with Heisenberg’s theory ($^3$). For the case of magnetization along [111], he found that the curves he obtained agree better with experiment than the curves calculated by Gans and Harlem ($^4$) on the basis of Heisenberg’s theory. He evidently sets this result in opposition to Heisenberg’s theory.

I call attention to a paper ($^5$) in which it was shown that this discrepancy is a consequence of an error in the calculations of Gans and Harlem. Curves correctly calculated according to Heisenberg’s theory ($^{5,6}$) agree satisfactorily with the experimental data.

No single theory describes the magnetization process exactly, but Heisenberg’s theory has the advantage that it is readily applicable to various problems. Thus, this theory and its subsequent modifications were recently used ($^7$) to interpret the reversible behavior of ferrites. Moreover, Akulov himself once ($^8$) used it.

Saint Paul, Minnesota,
USA

Received
December 12, 1956

REFERENCES

$^1$ N. S. Akulov, DAN, 106, 31 (1956).
$^2$ N. S. Akulov, Zs. f. Physik, 69, 78 (1931).
$^3$ W. Heisenberg, Zs. f. Physik, 69, 287 (1931).
$^4$ R. Gans, J. v. Harlem, Ann. Physik, 15, 516 (1932); 16, 162 (1933).
$^5$ W. F. Brown, Jr., Phys. Rev., 52, 325 (1937).
$^6$ R. H. Fowler, Statistical Mechanics, 2nd ed., N. Y., 1936, p. 520.
$^7$ D. M. Grimes, Bull. Am. Phys. Soc. (2), 1, 25 (1956).
$^8$ N. Akulov, E. Kondorsky, Zs. f. Physik, 78, 801 (1932); 85, 661 (1933).