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Magnetic force microscopy (MFM) is an imaging technique which is particularly well suited to studying magnetization patterns and other issues in magnetic recording physics. The technique provides high magnetic contrast, submicrometer resolution, requires a minimum of sample preparation, and can be used with both soft and hard magnetic materials. We have developed a MFM designed around a novel optical-fiber interferometer incorporating a laser diode, and have used it to study a variety of thin films of recording media. We have imaged transitions written with a recording head in both CoPtCr, a longitudinal medium in which the magnetization lies in plane, and CoCr, a perpendicular medium. The MFM revealed fine structure such as intrinsic media noise on virgin media, detail within magnetic transitions, and side-writing effects. We have also used the MFM to study the erase band created during overwrite under various conditions. In films of SmCo, a novel thin-film medium, the MFM revealed that there exists a minimum spacing between transitions below which the magnetization pattern cannot be sustained. In order to improve lateral imaging resolution, we have fabricated tips by sputter coating nonmagnetic tungsten tips with 50 nm of CoPtCr. Using these tips we have achieved resolution well under 100 nm.

All elements required for writing, storing, and reading information in a bubble lattice device have been designed and fabricated in a single test chip. Design considerations and operating margins are given for the five major components of the device: (1) write station (nucleation and wall state control in an isolated-bubble region); (2) read station (wall state discrimination and bubble detection in an isolated-bubble region); (3) storage (confinement and translation of a close-packed hexagonal bubble lattice); (4) isolated-bubble to bubble lattice transition; and (5) bubble lattice to isolated-bubble transition. All functions have been demonstrated on a single test device operating in a data-in, data-out mode. Initial error rates and sources of errors are discussed.