Magnetic Force Microscopy
Abstract: Magnetic force microscopy (MFM) is a widely used magnetic imaging technique, because MFM has a few ten nm spatial resolution and no need of special pretreatment. In recent years, the improvement of spatial resolution and functionalities is required for the research and development of magnetic materials and magnetic devices. We have developed a novel form of magnetic force microscopy called alternating magnetic force microscopy (A-MFM) for the imaging of DC and AC magnetic fields with the ultra high spatial resolution of less than 5 nm. A-MFM utilizes the frequency modulation of cantilever oscillation induced by applying off-resonant alternating magnetic force to a highly sensitive homemade magnetic tip. A-MFM is the first magnetic force microscopy technique that enables near-surface magnetic imaging. A-MFM has several new functionalities including a) zero detection of magnetic field, b) polarity detection of magnetic field and surface magnetic charge (N pole / S pole), c) stroboscopic AC magnetic field imaging, and d) DC magnetic field imaging with selectable measuring axis even at rough surfaces such as the fractured surface of permanent magnets. In this article, the recent progress of A-MFM is reported.
Key words: magnetic force microscopy, magnetic field imaging, magnetic recording head, magnetic recording media, permanent magnet