## 3 Results and Discussion
### MBN Measurements
The weaker magnetic field is capable of removing the remnant magnetization in the magnetically softer regions and suppresses the influence of the demagnetization process on MBN in contrast with regions that are harder. This is because the lower influence of demagnetization of MBN and the extracted MBN features can be found near the sheet edges. Figure 8 demonstrates that the aforementioned magnetic coupling and the presence of remnant magnetization in the sheet also affect the asymmetry of the MBN envelopes and the corresponding heterogeneity in the \(PP\) along with the sheet width. The presence of remnant magnetization makes the region magnetically softer, in contrast with the demagnetized state; see Figure 8. This effect is more developed in the RD, while the TD is nearly unaffected; see Figure 9.  
The remarkable asymmetry in the consecutive MBN bursts before demagnetization (see Figure 6) can be directly linked to the strong asymmetry in the MBN envelopes along the descending magnetic field (negative) and the ascending one (positive); see Figure 10. Demagnetization of the sample, which completely removes the remnant magnetization, makes the MBN envelopes nearly the same with no sensitivity to the direction of the altering field. It should also be noted that the \(PP\) suffers from the presence of remnant magnetization, most of all MBN features. The extremely high STDV of the \(PP\) discriminates this MBN characteristic with respect to its use for the monitoring of the surface state and/or stress state in real applications when the component is not sufficiently demagnetized (see also Supplementary Materials). Figure 7: MBN after demagnetization versus MBN before demagnetization: (a) MBN in the RD—side A and (b) MBN in the TD—side A. The _FWHM_ is the MBN feature linked to the range of magnetic fields in which MBN emission can be detected. This parameter is also quite sensitive to the exerted stress [39]. When the preferential orientation of the matrix is developed, the conditions for the initiation of DWs in different regions (layers, grains) are very similar, MBN bursts are very narrow, and _FWHM_ is low [40]. The 1100 MC MBN bursts and the corresponding _FWHM_ are typical for soft magnetic bodies when MBN occurs in quite a wide range of altered magnetic fields. Figure 8: \(PP\) along the sheet width: (**a**) \(PP\) in the RD—side A, (**b**) \(PP\) in the RD—side B; (**c**) \(PP\) in the TD—side A; and (**d**) \(PP\) in the TD—side B.  
\[v_{p}=\frac{dM}{dt}=(H-H_{c})^{q} \tag{1}\]0 \(PP\) after demagnetization versus \(PP\) before demagnetization: (**a**) \(PP\) in the RD—side A and (**b**) \(PP\) in the TD—side A. Moreover, due to the superimposed magnetization of the remnant with the altered external field, the _FWHM_ is higher (see Figure 11) since the conditions for unpinning DWs are very heterogeneous and directionally sensitive. The directional sensitivity can be proved by the higher differences between the _FWHM_ before and after demagnetization along with the sheet width in the RD and the TD; see Figures 11 and 12. \[v_{p}=\frac{dM}{dt}=(H-H_{c})^{q} \tag{1}\]1 _FWHM_ along the sheet width: (**a**) _FWHM_ in the RD—side A, (**b**) _FWHM_ in RD—side B, (**c**) _FWHM_ in TD—side A, (**d**) _FWHM_ in TD—side B.  
\[v_{p}=\frac{dM}{dt}=(H-H_{c})^{q} \tag{1}\]2 MBN envelopes before and after demagnetization; before demagnetization MBN, 302 \(\pm\) 32 mV and after demagnetization MBN 850 \(\pm\) 5 mV. Requirements considering sufficient demagnetization are associated with the magnetic field produced by the used sensor. These fields are too weak for unpinning DWs in all regions that contribute to MBN. The situation is briefly depicted in \[v_{p}=\frac{dM}{dt}=(H-H_{c})^{q} \tag{1}\]3 Figure 13a depicts the initial state without altering the external magnetic field and with the remnant magnetization coupled to the blue region of the opposite magnetization of that in the red region.