In-situ observation of magnetic domain structures in nanocrystalline soft magnetic materials by differential-phase-contrast scanning transmission electron microscopy

Soft and hard magnetic materials are becoming increasingly important for energy efficiency in transformers, motors, and inductors. To reveal the microscopic origins of their magnetic properties, it is crucial to observe magnetic domain structures with an external magnetic field at high spatial resolution. Differential-phase-contrast scanning transmission electron microscopy (DPC STEM) is expected to be a powerful technique for directly visualizing electromagnetic fields inside materials even down to atomic dimensions. In this study, we investigated the capability of DPC STEM for in-situ observation of soft magnetic materials. We observed three different soft magnetic materials with various coercivities and found clear differences in the observation results. These results suggest that DPC STEM has a great capability to directly reveal the microscopic origin of magnetic properties in magnetic materials.