Abstract

Electron holographywas invented for aberration correction, however it is now useful for observing electro-magnetic micro-fields or nano-fields. It is currently an indispensable technique not only for studying fundamental physics, but also for developing nanomaterials and nanodevices in industry. We have been developing new types of electron holography, such as phase-shifting electron holography to obtain higher sensitivity of phase measurements, real-time electron holography for dynamic observations, and electron tomographic holography for the three-dimensional analysis of electro-magnetic micro-fields. In addition, we have been trying to use these newtypes of holography for research and development in the industry. Recently we succeeded in observing dipolar ferromagnetic domain structures in ordered monolayer arrays of Co nanoparticles for the first time. In zero field-cooling experiments, we demonstratethe formation of micron-sized magnetically ordered regions with transverse domain walls, and a spatially varying moment order parameter. We also succeeded in visualizing dopant distribution in a GaAs model sample. This type of measurement is useful for developing solid-state laser devices.