Giant Heterogeneous Magnetostriction Induced by Charge Accumulation-Mediated Nanoinclusion Formation in Dual-Phase Nanostructured Systems

The fundamental origin of the giant magnetostriction in the dual-phase nanostructured systems is under energetic discussion in recent years. Previous studies have revealed that the formation of tetragonal nanoinclusions induced the enlargement in local magnetocrystalline anisotropy, leading to a strengthened magneto-elastic coupling coefficient, which was considered to promote magnetostriction. As the other key factor of magnetostriction, the influence of the nanoinclusions on the elastic constants of the lattices is still unnoticeably. In this work, we propose a mechanism based on the experimental and theoretical results of binary and rare-earth (RE) doped FeGa single-crystals. Doping traces of RE atoms effectively increase the density of nanoinclusions in the A2 matrix, because of the high selectivity of RE atoms so that they possess stronger bonding interaction with Fe atoms rather than Ga atoms. As a sequence, the elastic constant ς 12 significantly increases with the rising density of tetragonal nanoinclusions as opposed to a constant ς 11, resulting in a remarkable enhancement in magnetostriction due to the inversely proportional relationship between magnetostriction (λ 001) and ς 11 - ς 11. A superior magnetostriction of 390 ppm is obtained in the RE-doped single-crystal due to the lattice softening induced by the nanoinclusions. This model sheds light into the contribution of RE atoms to magnetostriction in FeGa single-crystals, and establishes a foundation for developing new-generation dual-phase magnetostrictive materials to achieve unprecedented levels of magnetostriction.