AC magnetic field frequency dependence of magnetoacoustic emission

It has previously been proved that there is a strong correlation between the low-frequency AC applied magnetic field amplitude dependence of the asymmetry of the magnetoacoustic emission (MAE) burst and the strength of the domain-wall-defect interaction in iron-base ferromagnets. The AC magnetic field frequency dependence of the asymmetry is investigated in the range of 1 to 200 Hz. When represented by the third moment of the rectified acoustic emission pulses, the asymmetry becomes a bell-shaped function of frequency with its center located around 25 Hz. The experiment is performed with low-carbon, high-yield stress steel specimens of three different levels of domain-wall-defect interaction strength. The results show that the increase in the interaction strength causes a vertical down shift of the asymmetry in the entire frequency range investigated