ABSOLUTE MAGNETOMETRY OF THIN COBALT FILMS AND CO/CU MULTILAYER STRUCTURES AT NANOMETER SPATIAL-RESOLUTION

The absolute measurement of magnetization in thin magnetic specimens at nanometer spatial resolution has been made possible by implementing two off-axis holography modes in a scanning transmission electron microscope (STEM). The absolute mode of STEM holography displays a linear change in phase difference for regions with constant magnetization and the slope determines the absolute value of magnetization in the specimen. The differential mode of STEM holography displays a constant value of phase difference for regions with constant magnetization, which simplifies the identification of magnetic structures in the specimen and the determination of domain wall profiles. Taking into account the high spatial resolution of a STEM instrument, STEM holography provides a valuable tool for quantitative investigations of magnetic structures at the nanometer level.