Domain Wall Profiles in Magnetic Films

An inversion procedure for determining a domain wall profile from the associated Lorentz-microscopy electron-density distribution is discussed. This procedure is verified by application to computer-simulated electron-density distributions derived from assumed wall profiles. The experimental realization of the inversion procedure is demonstrated for high-resolution Lorentz micrographs of films ranging in thickness from 100 to 500 Å; unreliable profiles were obtained for thicker films. The importance of correcting for the effects of nonmagnetically scattered electrons is emphasized; these effects increase with increasing sample thickness and defocussing distance. The experimental domain wall profiles exhibit first a rapid, then a slow increase of wall angle with distance from the wall center. Wall widths derived from these profiles are consistent with theoretical predictions if corrections are made for nonmagnetic scattering; if such corrections are not made, the large widths reported by other authors are obtained.