In-situ observation of magnetic domain reversal during magnetic viscosity of permanent magnets

Magnetic viscosity analysis is a widely studied topic in understanding the stability and magnetization mechanisms of magnets. However, observing the minute changes in magnetic domains during the magnetic viscosity process poses a challenge in research. To address this issue, a self-made in-situ magnetized sample holder was used in this study to observe the dynamic evolution of domain structures in alnico alloy during magnetic viscosity. The findings indicate that the domain reversal during magnetic viscosity is largely irreversible, with only minor reversible changes observed in the inhomogeneous region. The magnetization reversal in alnico alloy occurs through the reversal of α1 phases, which follows a single domain particle reversal mode. The zero-field activation energy (E0) of alnico alloy is determined as 3.30 × 10−17 J, and the coercivity field without thermal disturbance (H0) is measured at 1779.19 Oe. This research method proves to be a valuable tool in the study of magnetic materials.