Extraordinary magnetoelasticity and lattice softening in bcc Fe-Ga alloys

Clark, A.
Hathaway, K.
Wun-Fogle, M.
Restorff, J.
Lograsso, Thomas
Keppens, V.
Petculescu, G.
Taylor, R.
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Extraordinary magnetostrictive behavior has been observed in Fe-Ga alloys with concentrations of Ga between 4% and 27%. λ100 exhibits two peaks as a function of Ga content. At room temperature, λ100 reaches a maximum of 265 ppm near 19% Ga and 235 ppm near 27% Ga. For compositions between 19% and 27%, λ100 drops sharply to a minimum near 24% Ga and exhibits an anomalous temperature dependence, decreasing by as much as a factor of 2 at low temperatures. This unusual magnetostrictive behavior is interpreted on the basis of a single maximum in the magnetoelastic coupling ∣b1∣ of Fe with increasing amounts of nonmagnetic Ga, combined with a strongly temperature dependent elastic shear modulus (c11c12) which approaches zero near 27% Ga. λ111 is significantly smaller in magnitude than λ100 over this composition range, and has an abrupt change in sign from negative for low Ga concentrations to positive for a concentration of Ga near 21%.


Copyright 2003 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

The following article appeared in Journal of Applied Physics 93 (2003): 8621 and may be found at http://dx.doi.org/10.1063/1.1540130.

iron alloys, gallium alloys, magnetoelastic effects, magnetostriction, ferromagnetic materials, elastic constants, soft modes, elastic moduli