Magnetic coercivity patterns for magnetic recording on patterned media

Magnetic patterns were created by locally altering the magnetic coercivity of a perpendicular anisotropy film by ion irradiation. The resulting pattern, after dc magnetizing, consists of regions having alternating up/down magnetization patterns in remanence. In this case, the magnetization of the soft magnetic material in the exposed segments is reversed and stabilized by the demagnetization fields of the adjacent unexposed media. A magnetic pattern generated in this manner can be used as a type of servo pattern for recording head positioning. An accuracy in positioning of better than 10 nm was demonstrated and deliberate magnetic patterns were written and read back by addressing individual 80 nm single-domain nanostructures