Induced additional anisotropy influences on magnetostriction of giant magnetostrictive materials

Initial magnetization realignments induced by a uniaxial compressive pre-stress or transverse magnetic annealing can enhance effectively strain output of giant magnetostrictive materials. However, differing from the use of stress that induces in-plane anisotropy, it is found that magnetic annealing is capable of resulting in a uniaxial magnetic anisotropy in 110 grain-aligned TbDyFe polycrystals. We find the critical induced additional anisotropy to generate a uniaxial magnetization alignment along only one easy axis that is essential to realize 90°domain evolution during initial magnetization stage, hence yielding a large magnetostriction under modest switching fields. By a phenomenological approach based on magnetization rotation, we explain quantitatively how the induced additional anisotropy energy influences the magnetostrictive behaviors under coupled magnetomechanical loadings. Consequently, distinctive approaches to further enhance the saturation magnetostriction are suggested through the combination use of induced additional anisotropy and compressive pre-stress.