Submicron Magnetizing and Its Detection Based on the Point Magnetic Recording Concept

Recent intensive studies by scanning probe microscope (SPM) on the recording and detection of extremely minute bit patterns have assumed increasing importance in the field of magnetic recording, because the sharp magnetic tip of the SPM can be used as a kind of micro-manipulator of magnetic domains. This paper investigates submicron magnetic bit recording and detection, in which the tip of a magnetic force microscope (MFM) is used as both the recording head and the magnetic field detector. In the recording procedure, the MFM tip and an excitation coil concentrate magnetic flux as the tip is brought into contact with the medium. When scanned above the medium, the mechanically modulated tip can easily be used to measure the magnetic force gradient by detecting changes in the tip modulation amplitude. Regions with a diameter of about 400 nm can be magnetized and can be erased by a reverse magneic field. Sharper tips will enable magnetization of even smaller regions.