(a) Room temperature magnetostriction curves for GdFe₂, Gd_0.9Tb_0.1Fe₂, Gd_0.7Tb_0.3Fe₂, and Gd_0.5Tb_0.5Fe₂ under applied fields of 10 kOe and 50 kOe. The schematically mesoscopic explanations for anisotropic magnetostriction due to the switching of the noncubic ferromagnetic (ferroelastic) domains with different crystal symmetries, respectively: (b) for GdFe₂ with tetragonal phase; (c) for Gd_0.9Tb_0.1Fe₂, Gd_0.7Tb_0.3Fe₂, Gd_0.5Tb_0.5Fe₂ with rhombohedral phase. The small rectangles and rhombuses represent the unit cell symmetry to be tetragonal and rhombohedral, respectively. ΔL is the anisotropic magnetostriction due to magnetic field H.