Lorentz Microscopy of Magnetic Domain-Wall Pinning on Artificially Introduced Holes in Electrical Steel Sheets

Abstract

To investigate the interaction between magnetic domain walls and defects in an electrical steel sheet by transmission electron microscopy, size-controlled holes were artificially introduced into specimens by a focused ion beam. By applying an external magnetic field in a transmission electron microscope, the magnetic domain structures around the holes were dynamically observed by Lorentz microscopy. Similar magnetic domain structures were observed around the holes, but the domain-wall pinning strength was found to depend on the hole size. Micromagnetic analysis was performed to ascertain the magnetic domain structures around the holes and to investigate the change in the magnetic energy during domain-wall pinning.