High-resolution visualizing techniques: Magnetic aspects

Magnetic imaging plays an important role in clarifying the phase transformation mechanisms and/or the correlation between nanostructures and materials functions in magnetic compounds. Methods based on transmission electron microscopy (Lorentz microscopy and electron holography) are powerful tools for analyzing the aforementioned aspects, because these methods allow for nanometerscale resolution and can be effectively combined with peripheral techniques such as electron diffraction and high-resolution transmission electron microscopy (lattice imaging). This chapter explains the essence of magnetic imaging and discusses recent topical studies on magnetic functional materials, to which these techniques have been applied to obtain useful information that helps understand the mechanisms underlying the extraordinary material properties. In particular, this chapter focuses on colossal magnetoresistive manganites and ferromagnetic shape-memory alloys, both of which are closely related to the issues of the disorder and straininduced complexity.