Effect of magnetising frequency and stress on magneto-acoustic emission from 3% Si-Fe crystals

The magneto-acoustic emission (MAE) from a 3% Si-Fe single crystal splits into two peaks at the coercive force during half a cycle of the B-H hysteresis loop, one associated with the change of strain due to the nucleation and the other due to the annihilation of domain walls. The emission increases as the magnetising frequency increases; however, the rate decreases above the frequency where the skin-depth effect becomes apparent. The emission from 3% Si-Fe polycrystals increases with tensile stress up to 11.2 x 1O⁶ N m^-2, then it decreases with further stressing. The source mechanism of the MAE is discussed in terms of the change of strains: One is related to the magnetostriction coefficient due to the nucleation and annihilation of domain walls, and the other is related to the magnetostriction due to the 90 ° domains.