Experimental evaluation of domain wall dynamics by Barkhausen noise analysis in Fe₃₀Co₇₀ magnetostrictive alloy wire

Magnetic Barkhausen noise (MBN) plays significant roles to describe the dynamic of domain walls (DWs), but an in-depth understanding of the correlation between Barkhausen effect and magnetostrictive effect during magnetization process is still limited. In this study, we investigated MBN signals and the frequency spectra in a high-magnetostrictive Fe₃₀Co₇₀ alloy wire (λ_s = 102 ppm) by evaluating the stress effects on MBN profiles at the stress range of 0–150 MPa using tensile test machine. The results from MBN profiles revealed that MBN in the high magnetic field region was responsible for the localized changes of magnetic flux density, dB/dt induced by magnetic distortion related to non-180° DWs or the magnetization rotation. In MBN spectra, the peak shift towards lower frequencies with the increase of stress indicates that the rough pulse-like MBN outbreaks increase, and it results mainly from the increase of DW jumping length which is caused by the pinning effect at grain boundaries where DW energy is relatively high. In addition, stress dependence of the root mean square (RMS) value of MBN showed a good sensitivity (0.038 mV/MPa). Overall, these findings indicate that new MBN measurement system utilizing magnetostrictive materials can be helpful for a wide range of applications such as mechanical stress sensors and energy harvester systems.