Electron microscopy and the study of microstructure and domain structure of magnetic materials

Five different electron optical techniques to characterize magnetic domains and domain walls in ferromagnetic materials are reviewed. It is shown that one can choose one or more of these techniques to solve a given problem depending on the nature of the information needed, the resolution level desired and the sophistication of the instrument available. Lorentz microscopy in a transmission electron microscope is a clear choice for most problems although spin-polarized scanning electron microscopy or magnetic force microscopy are better suited to non-destructive surface studies, and differential phase contrast microscopy is preferable for quantitative study of domains in thin specimens. Electron holography is capable of providing contour maps corresponding to lines of force distribution as well as quantitative data on flux distribution. In the near future, it should become possible to combine a few of these techniques with computer simulation to obtain three-dimensional domain wall distributions in bulk ferromagnets.