Large magneto-chemical-elastic coupling in highly magnetostrictive Fe-Ga alloys

摘要

The strong softening of the tetragonal shear elastic constant (C') is the main reason for the second magnetostriction peak observed in Fe_(100-x)Ga_x alloys. Here, we study the coupling between chemical order and magnetism with the aim to understand the origin of the elastic softening. We demonstrate that C' strongly depends on the degree of order of Ga atoms in α-Fe. The B_2 type ordering proves to have an important role on the elastic softening for x < 19%, whereas the extreme shear lattice softening and the anomalous temperature dependence of C are found to be due to the strong magnetochemical coupling in the DO_3 phase.