Quantitative mapping of the magnetic induction distribution using Foucault images formed in a transmission electron microscope

A method of producing quantitative maps of the magnetic induction distribution using a conventional transmission electron microscope (TEM) is presented. The magnetic induction maps are constructed from four series of Foucault images taken with small incremental tilts of the incident illumination. By reciprocity, this is equivalent to differential phase contrast (DPC) which is usually performed in a modified scanning transmission electron microscope (STEM), and whilst maintaining all the benefits of its STEM counterpart, the DPC images formed by the method presented in this paper are particularly suited to studying thick magnetic films. Unlike the other quantitative Lorentz imaging techniques, the magnetic induction maps constructed from Foucault images can be produced on a standard TEM modified with a low-field pole-piece. Images from two types of cross-tie domain wall are shown as examples which have a spatial resolution of approximately 8 nm.