Stress-induced butterfly and square-like magnetostriction loops transition

The stress-induced magnetic domain switching in FeGa thin films is studied using phase-field method. In particular, the magnetic field is applied along the [110] direction and biaxial stresses are applied along [100] and [010]. A compressive pre-stress corresponds to a smaller coercive magnetic field while a tensile pre-stress corresponded to a larger coercive field. At the same time, it is also found that the transition between butterfly and square-like magnetostriction loops occurs at the critical opposite biaxial stress state. The two different evolutions correspond to two different mechanisms: one is that the single domain swings across a fan area back and forth; the other is that the single domain turns a clockwise circle. The results can be explained by the stress tuned anisotropy energy well.