Three-dimensional analysis of magnetization distribution by MFM and electron holography

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The aim of this research project is to develop a new technique that reveals a magnetization distribution in three-dimension and its application to nanostructured magnetic materials. Electron holography is combined with MFM (magnetic force microscopy) in ordered to observe both the in-plane component of magnetic flux and the stray magnetic field that is approximately perpendicular to the foil plane of the specimen.As an achievement in this project, we have established a computer simulation technique, by which a holographic result (i.e., information of magnetic flux) can be converted to a magnetization distribution in a thin-foiled specimen. MFM observations were conducted for the same specimen as that of the holography study ; therefore, the magnetization distribution was revealed in three-dimension. In fact the devised method was applied to magnetic recording systems and other magnetic materials. We have also developed a unique method to apply a magnetic field by using a sharpened magnetic needle-the needle produces a magnetic field near 1T, which is large enough for performing in situ observations of a magnetization process within a transmission electron microscope. Many important results were obtained within the research period, and they were published in major journals such as Phys.Rev.Lett., Appl.Phys.Lett., J.Appl.Phys., etc.