Magnetization Response of the Bulk and Supplementary Magnetic Domain Structure in High-Permeability Steel Laminations VisualizedIn Situby Neutron Dark-Field Imaging

Power transformers, key components of an electrical grid, have cores made of iron-silicon ``electrical steel'' alloys. The structures of magnetic domains in these highly anisotropic, grain-oriented laminates chiefly determine a core's key properties, and thus its performance. The authors use neutron grating interferometry to observe-0.22em these domain structures and their response to s00ext00exa00ext00exi00exc external magnetic fields. This direct access to a sample's magnetic structure will enable physicists to improve our understanding of macroscopic magnetic phenomena in bulk ferromagnets, and will help engineers optimize these alloys and systems.