Submicron magnetizing and its detection based on the point magnetic recording concept

The authors investigate submicron magnetic bit recording and detection using a tip of a magnetic force microscope as both the single-pole head and the magnetic field detector. To attain high sensitivity, the magnetic tip mounted at the end of the 200-μm cantilever is photolithographically fabricated as a monoblock. The recording medium is double-layered cobalt-chromium and permalloy. The Permalloy tip and an exciting coil placed on the side of the medium opposite the tip (radius=0.8-0.1 μm) concentrate magnetic flux when bringing the tip into contact with the medium. The mechanically modulated tip scanning about 400-120 nm above the medium easily detects the changes of the magnetic force gradient. Regions about 1 through 0.5 μm in diameter can be magnetized, and they can be erased by an inverse magnetic field. Sharper tips will allow magnetization and its detection in even smaller regions