Origin of magnetostriction in Fe–Ga

Abstract

This paper investigates the origin of large magnetostriction in Fe–Ga alloys using small-angle neutron scattering (SANS) and Kerr microscopy. The SANS data for a single-crystal, electron irradiated, and quenched Fe81Ga19 sample under externally applied magnetic and elastic fields revealed the existence of magnetostrictive nanoclusters spaced at ∼15 nm apart that have a different magnetization than the A2 matrix. Combining the SANS results and the magnetization orientation obtained from the magnetic domain images using a Kerr microscope, it appears that the nanoclusters contribute significantly to the macroscopic magnetostriction.

Atomic-scale modeling of nanostructure formation in Fe–Ga alloys with giant magnetostriction: Cascade ordering and decomposition

“…TEM studies [6][7][8][9][10] have demonstrated that a Fe-Ga alloy within this range is not the homogeneous disordered bcc A2 phase, but rather is a coherent dispersion of nanoscale clusters. A polarized neutron diffraction study under an applied magnetic field [27] showed that these clusters are tetragonal and that the orientation of their tetragonal lattice is changed by the application of a magnetic fieldthe effect predicted by the KV model of extrinsic model of GM [4,5].…”

Magnetic domain observations in Fe–Ga alloys

“…In light of these promising technological properties, Fe-Ga solid solutions have recently been the focus of intense studies primarily with the goal of elucidating the nature of the observed unusually large magnetostriction [5]. In order to answer the question if this striction is a volume property or brought about by defects (or clusters) [7], X-ray [8], and neutron diffraction [9] as well as transmission electron microscopy [10], Differential X-Ray Absorption Spectroscopy [11], and small angle neutron scattering (SANS) [12,13] experiments were undertaken. This paper reports on the macroscopic domain configurations in slow-cooled Fe 83.5 Ga 17.5 , quenched Fe 83.5 Ga 17.5 , and quenched Fe 81 Ga 19 single crystals.…”

Magnetic force microscopy investigation of the static magnetic domain structure and domain rotation in Fe-x at. %Ga alloys

“…%Ga using small angle neutron scattering, where Wuttig et al 23 have shown the presence of magnetic nanoregions with characteristic size of about 10-15 nm. These results, in conjunction with our MFM images, provide insight into an unorthodox magnetic domain rotation mechanism, where rotation occurs via domain nonuniformities, rather than by a homogenous rotation of the magnetization vector.…”