The Determination of Domain Wall Thickness in Ferromagnetic Films by Electron Microscopy

Domain walls in ferromagnetic films may be imaged by out-of-focus electron microscopy. The wall images are light or dark depending on the relative sense of the magnetization either side of the wall, the incident electron beam being diverged or converged about the wall position. A relationship is obtained between the image widths of light and dark walls, for all distances out of focus and the true domain wall width. Values obtained for evaporated polycrystalline films are (to ±30%) permalloy, 1800 Å; iron, 1000 Å; nickel, 550 Å.