Trends in Magnetic Storage Technology
Systems & Materials for Information storage (SMI)
MESA+ Research Institute, University of Twente, Enschede, The Netherlands
In the never ending quest for higher areal storage density magnetic recording is still the keyplayer. Nowadays commercial hard disk drives have capacities in the tens of gigabits and data densities very close to 100 Gb/sq.in. There are no fundamental limitations to realize hard disk densities of 1 Tb/sq.in using the perpendicular magnetic recording mode. In the longitudinal mode of magnetic recording the superparamagnetic behavior of the particles/crystals in the bit cell are limiting higher densities. To overcome the superparamagnetic limit the use of magnetic nanoparticles with extremely high anisotropy are developed. But in the meantime also new types of high flux density Bs write heads must be developed to write the bits in this media having very high coercivities. For yet higher density recording, heat assisted magnetic recording (HAMR) is being pursued. Here a combination is made by using a laser, heating the media and the magnetic field from the write-head. Perpendicular recording could facilitate the use of higher anisotropy and more stable media due to a higher thickness of the magnetic thin film. Another approach for pushing the density of perpendicular recording is the use of patterned media in which bits consist of a single dot of magnetic material. The dot-magnetization is directed either upward or downward and can be read/write by an array of probes. In this presentation various activities in SMI will be highlighted and from this presentation it will be clear that magnetic data storage is already one of the applications of nanotechnology.