It is well established that the response of devices based on the
giant magnetoresistance (GMR) effect depends critically on film
microstructure, with parameters such as interfacial abruptness, the
roughness and waviness of the layers, and grain size being crucial.
Such devices have applications in information storage systems, and are
therefore of great technological interest as well as being of
fundamental scientific interest. The layers must be studied at high
spatial resolution if the microstructural parameters are to be
characterized with sufficient detail to enable the effects of
fabrication conditions on properties to be understood, and the
techniques of high resolution electron microscopy, transmission
electron microscopy chemical mapping, and atom probe microanalysis are
ideally suited. This article describes the application of these
techniques to a range of materials including spin valves, spin tunnel
junctions, and GMR multilayers.