Characterization of patterned magnetic media prepared via nano-lithography.

摘要

This dissertation investigated the feasibility of using conventional magnetic recording technology for data storage perpendicular patterned media prepared by high-resolution lithography. The study was motivated by the potential onset of thermal instability in conventional longitudinal recording. Replacing conventional media, where single bit of information is represented by hundreds of small single domain magnetic grains, by the media where a single bit of information is represented by a single but larger single domain magnet offers a potential solution to stable magnetic recording at densities beyond 100Gb/in 2.; Stable single domain magnetic columns were embedded in a hard, smooth, and non-magnetic substrate. The samples were prepared by combination of electron beam lithography, dry etching, oxidation, electrodeposition and polishing procedures. Electron beam lithography was used to define the dot arrays. The patterns were transferred into the AlGaAs/GaAs substrate by chemically assisted ion beam etching. Wet thermal oxidation was used to convert the GaAlAs layer into Al₂O₃. The holes in Al₂O₃ and GaAs were filled with nickel by electrodeposition, and polishing was used to remove excess material and provided a smooth sample surface appropriate for slider contact.; The samples were studied by Magnetic Force Microscopy and Scanning Magneto-Resistance Microscopy. These techniques revealed that the single domain columns were magnetically stable, and are read non-destructively by commercial magneto-resistive sensors. The read process was theoretically modeled and compared to experimental results. Following the stable reading of the columns, the controlled data storage in single column per bit perpendicular patterned media was demonstrated. The patterned media write process using longitudinal magnetic recording write heads was investigated. Detailed studies revealed that the perpendicular components of the magnetic fields under the poles of the thin film write heads are responsible for the magnetization reversal of the columns. Data storage was also demonstrated in high density patterned media structures.