9707033 Indeck Magnetic information storage density is still some three orders of magnitude from the room temperature superparamagnetic limit, but the volume of storage medium per stored bit is shrinking rapidly. The research proposed here addresses issues of storage density and stability related to the magnetic microstructure of storage media. A microstructural magnetic unit of a medium is the smallest piece of the medium whose magnetization can be altered. Magnetic units may or may not coincide with the medium's physical microstructural units (particles, grains). Each stored bit in most existing or proposed magnetic storage systems comprises many microstructural magnetic units, and in all practical and economically viable systems the microstructural units have widely varying characteristics (particle, grain, or cluster size, orientation, etc.). In a given medium we can infer the size of the micromagnetic unit from electron or probe microscopic images, or indirectly from macroscopic experiments or modeling results. We propose to develop an additional direct measurement using the anomalous H the storage medium environment the stored bit is subjected to forces that shorten its thermal decay lifetime. We will all effect. In experimentally quantify the effect of temperature on the write process, medium noise, and stability. The experimental work will be paralleled by sophisticated modeling. In this modeling a planar medium is represented as a tessellation of uniformly magnetized tiles. We have pioneered a new (Voronoi) tessellation that avoids the artifacts introduced by the almost universally used regular tiling, and we will use our model for studies of the temporal and thermal effects on the write process, noise, and stability. We are working on ways to deduce the intrinsic medium properties required for modeling from measurements of extrinsic parameters. Our demonstration of the determinism of medium noise has been the seed of a separate noise precompensation that offers the promise of a major storage capacity increase. This program will be supported with experimental results on media and transducers. ***
