Media Fabrication and Characterization Systems for Multilevel Three-Dimensional Magnetic Recording
The data storage industry recently substituted its five-decade-old technology (longitudinal magnetic recording), which reached its fundamental limitations due to thermal instabilities in the recording media, with perpendicular magnetic recording. Nonetheless, the lifetime of this newly adopted technology and other next generation alternatives including heat-assisted magnetic recording (HAMR) and bit patterned media (BPM) is comparably short. In order to defer the superparamagnetic limit substantially beyond 1 Tbits/in^2, it may be necessary to stack information in a third (vertical) dimension.
This vertical stacking underlies the concept of multilevel (ML) three-dimensional (3D) magnetic recording and memory. In 3D magnetic devices, information is recorded, not only on one surface (as in all modern 2D applications), but in the entire 3D bulk of the recording media. As a result, substantially larger amount of data could be recorded on the same surface area (as compared to any 2D alternative). This study addresses design configuration, media fabrication, and characterization techniques for a particular ML 3D magnetic recording device. A newly developed ML 3D magnetic recording media enables selective reading and writing of up to 4 distinct signal levels, in comparison to only two signals in conventional 2D-based magnetic recording media. It is believed that at least over six layers (or over 2^6 = 64 signal levels) could be independently accessed in a ML 3D magnetic recording device. Gallium ion implantation as a potential method to alter the magnetic properties of 3D media is also discussed.
Furthermore, with every emerging technology, both fabrication systems and characterization techniques must be developed. One of the most crucial characterization tools, which enable the direct visualization of the smallest bit of magnetic information, is Magnetic Force Microscopy (MFM). MFM is thus an integral part of the development and characterization of ML 3D magnetic recording devices. Nevertheless, the best lateral resolution conventional state-of-the-art probes can produce under ambient conditions is limited to about ~ 25 nm. In this study, newly developed fabrication techniques for MFM probes are presented. Specifically, plateau probes to enhance the overall capabilities of MFM and high lateral resolution (below 10 nm in ambient conditions) multi-domain MFM probe. The enhancement in MFM capabilities has the potential to facilitate the development of HAMR, BPM, and ML 3D magnetic systems.