TABLE OF CONTENTS Energy-filtered transmission electron microscopy (EF-TEM) is a rapidly developing field for high spatial-resolution chemical imaging. With an energy filter, images (or diffraction patterns) formed by electrons with specific energy losses can be obtained (Fig. 2.44) (Reimer, 1995), Here we demonstrate a few applications of EF-TEM.
Magnetic multilayers (MLs) with giant magnetoresistance (GMR) effect have huge promise for future technology (Baibich, et al., 1988). Among different types of GMR MLs, NiFe/Cu based MLs are regarded as good candidates because their high MR ratios and field sensitivity for magneto-electronic device applications. Since the prominent physical property of GMR can only occur in MLs with sub-layers 1-2 nanometers thick, the microstructure of MLs plays an important role in oscillatory exchange coupling between magnetic layers and in spin-dependent electron scattering. It has been reported that the GMR effect is strongly dependent on the microstructure of the NiFe/Cu films (Miyamoto, et al., 1996; Naoe, et al., 1994; Nakatani, et al., 1993). For example, it is proposed (Pettit, et al., 1997) that pinholes in the Cu spacer layers in NiFe/Cu MLs may be responsible for the ferromagnetic coupling of neighboring magnetic layers and will lead to strong biquadratic coupling. But there is not enough experimental result to support such speculation.
Columnar crystallites (CCs) were found as a prominent structure character in these films (Fig. 2.47). The CC starts from the Fe buffer and penetrates all the sub-layers upward to the surface of the film. Similar...
