Three-dimensional Visualization of the Magnetic Microstructure in Bulk Fe-6.6 Pct Si

Magnetic materials such as Fe-Si alloys are magnetized by the rearrangement of their magnetic microstructure and domain wall motion. Understanding magnetic microstructures in the interior of a ferromagnet is essential for the control and reduction of energy losses in electrical devices. The three-dimensional magnetic microstructure of solids is still unknown due to the lack of an appropriate observation technique, and the magnetic domain wall structure inside a ferromagnet has never been observed with sufficiently high resolution. The first observation of the 3D magnetic microstructure of an Fe-6.6 pct Si alloy with a high spatial resolution is reported. The domain walls known to exist inside positive anisotropy cubic materials, i.e., the 180-deg domain walls and the 90-deg domain walls, were analyzed for the first time. The structure and orientation of the domain walls were found to be very different from the prediction of current theoretic models.