Tuning magnetostriction of Fe–Ga alloys via stress engineering

Stress has a strong impact on the magnetization and magnetostriction of magnetic materials due to the magneto-elastic coupling. It offers a clue to understand the 2–5 times enhancement on the magnetostriction of Fe–Ga alloys with rare-earth elements doping. In this article, the stress states of melt-quenched and melt-spun (Fe_0.83Ga_0.17)_100-xTb_x (x = 0–0.47) alloys were measured by high energy X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) technique. The macroscopic residual and microscopic stress of different Tb doped alloys were deduced from the shift and broadening of diffraction peaks and the deviation of the identified 1st Fe–Fe and 2nd Ga–Ga bond length. Rietveld refinement confirmed that the dissolved Tb atoms can replace the Fe/Ga site while small-angle neutron scattering (SANS) showed the presence of Tb-rich nanoscale precipitates. The effect of external stress loading and Tb doping on magnetization and magnetostriction of the modified Fe–Ga alloys was compared and discussed. We propose that the magnetization and magnetostriction of Fe–Ga alloys can be controlled through stress engineering by manipulating the magnetic domain structure through chemical doping or mechanical loading.