Magnetic Domain Structure Analysis of Nanocrystalline Magnetic Materials by Electron Holography

摘要

The principles of electron holography and its application to magnetic domain structure analysis of nanocrystalline magnetic materials are reviewed on the basis of the experimental results recently obtained by the author and his colleagues. The electron holography system was established by introducing a biprism and a special objective lens into a conventional electron microscope. With this system, the magnetic domain structures of nanocrystalline soft magnetic Fe-Cu-Nb-Si-B materials subjected to various heat treatments were clarified. The dependence of magnetic domain structures on the composition of nanogranular Co-Zr-O films was also clarified in detail. Finally, in nanocomposite Nd-Fe-B magnets, the detailed distribution of lines of magnetic flux was visualized at a nanometer scale. It was found that the distribution of lines of magnetic flux observed was directly related to the magnetic properties, such as coercivity and remanence.