Patterned media for future magnetic data storage

Abstract

One strategy to delay the onset of superparamagnetism and achieve magnetic storage densities approaching 1 Tb/in. 2 is the use of lithographically patterned magnetic media. While one of the main advantages enjoyed by magnetic recording is low cost due to use of featureless media, there are several advantages that may be realized by patterning the medium in a hard disk drive. The commercial success of patterned media will of course depend on the relative costs and gains. In particular, there are three main types of disk patterning proposed, each requiring a different length scale of patterned feature. Patterning of servo marks for maintaining the head position on-track, the fabrication of discrete tracks, and the fabrication of discrete bits have all been proposed and will be discussed. For discrete bit recording single domain magnetic islands are required, and one approach to fabricating these, by depositing magnetic films onto prepatterned substrates, is described. The switching characteristics of the islands as compared to those of the full film, along with initial recording results are presented.

Investigating the effect of a stress-based uniaxial anisotropy on the magnetic behaviour of La0.7Sr0.3MnO3elements

“…The Gilbert damping constant was set to α = 0.5 to allow rapid convergence in calculations. Technologies based on nanomagnets typically have critical dimensions below 200 nm [10], so a range of rectangular thin film elements were investigated, where the breadth was kept constant at 160 nm, and the length varied in integer multiples of the width to explore the effect of aspect ratio. The uniaxial anisotropy, K U , is directed along the [001] axis, with the hard axis being along , as illustrated in figure 1.…”

The Head-Disk Interface Roadmap to an Areal Density of Tbit/in2

“…It is remarkable to realize that the error rate of the stored digital signal that is being read back improves approximately by about 2x for every 0.3-0.5 nanometer of decreased HMS. In addition to relentless demand for novel, ultrathin protecting films of overcoat and lubricant, and subnanometer air gap between the disk and the head, alternative recording technologies presently being contemplated involve heating the disk to over 500 ∘ C (heat-assisted magnetic recording or HAMR) [10][11][12] and/or physically isolating magnetic bits on small islands of sub-30 nm in physical dimensions (bit-patterned recording or BPR) [13][14][15][16].…”

Miniature Engineered Tapered Fiber Tip Devices by Focused Ion Beam Micromachining

“…Originally, FIB processing was used for mask repair (Liang et al, 2000), integrated circuit chip repair/modification (Liu et al, 2006), cross-sectional imaging of critical parts of semiconductor devices and sample preparation for transmission electron microscopy (Daniel et al, 1998;Hopman et al, 2008;Jeon et al, 2010). Besides these applications, FIB milling can also be used to assist carbon nanotube growth and manipulation (Hofmann et al, 2005;Deng et al, 2006), pattern magnetic data storage media (Terris et al, 2007) and structure hard-to-etch materials like SiC or LiNbO 3 . In the field of optoelectronics, there have been extensively studies toward utilizing the FIB as a machining tool to fabricate planar micro-optical components with low surface roughness for integrated optical circuits, for example, the end facet mirrors, ring resonators, gratings and photonic crystals (Hopman et al, 2008).…”