TABLE OF CONTENTS Lorentz microscopy has been used extensively for the past 40 years to study magnetic domain structure and magnetization reversal mechanisms in magnetic thin films and elements. In this chapter, the principal imaging and diffraction modes are reviewed, both qualitative and quantitative. In addition, a description of the instrumental and specimen requirements is included, and in the final section, the application of the various techniques to the study of spin-valve and spin-tunnel junction layered structures is discussed as a means of illustrating the type of information that can be obtained.
Transmission electron microscopy (TEM) was one of the earliest techniques to be used for the imaging of magnetic domain structures in magnetic materials (see, for example, [1] , [2]). A principal motivation for the use of TEM for the analysis of magnetic domain structure is that many applicable magnetic properties are extrinsic rather than intrinsic to the materials themselves; in other words, they depend critically on the local microstructure and composition of the material. A detailed knowledge of both the physical and magnetic microstructure is, therefore, essential if the structure-property relation is to be understood and materials with optimized properties are to be produced. Some of the materials of interest are markedly inhomogeneous, with features on a sub-50 nm scale playing an important role in influencing the magnetization reversal mechanism. For example, the grain size in a spin-valve structure is typically on the order of 10 nm, and variations in magnetic properties between grains...
