Discrete Track Recording Research Articles

A study of FIB-patterned discrete track recording media by spinstand read/write testing and scanning probe microscopy

We have developed a new technique of quick fabrication and testing of discrete track recording (DTR) media for DTR concept and insight. DTR media by focused ion beam (FIB) patterning have been studied by spinstand read/write testing and scanning probe microscopy. DTR media show smaller magnetic track width and better signal separation between adjacent tracks and therefore higher track density than that of continuous media due to reduced side fringe effect and edge noise. It was also found that at a designed groove depth of 4–8 nm, the shallow FIB etched grooves already provide good isolation between adjacent tracks, indicating the importance of ion beam induced modification of magnetic properties in film media over physical modification of disk surface topography.

Modeling and design of discrete track recording media

In this paper, modeling and design of discrete track recording (DTR) media are done. The DTR media consists of lands on which the data is stored and recessed grooves that provide the magnetic isolation between adjacent data tracks. A simple model is formulated which assumes writing occurs over the land as well as the entire groove, with only a degradation due to the spacing loss in the groove. To account for this spacing loss, measurements are made on disks with different overcoats and an empirical expression for the spacing dependence is derived. The total spacing loss included the normal -55 d//spl lambda/ dB Wallace read spacing loss as well as the empirically derived write spacing loss expression. The maximum signal level from the grooves or adjacent lands is required to be 30 dB lower than for the signal on the land being read. A plot of groove depth requirements is done for different areal densities for given magnetic read widths. As these read widths become larger, a greater portion of the read sensor would detect transitions in the groove, and thus the groove depth must become larger. For the 120 Gb/in/sub 2/ design, a filling factor of 2/3 translates to a groove width of 65 nm. Widening the magnetic read width to half the track pitch would require a groove depth of 26 nm, a value 2.5 times smaller than the width. For filling factors 0.6 and 0.7, there is a 1 dB improvement in media signal-to-noise ratio (SNR) for modest groove width-depth ratios of 3, over a conventional flat disk.

Recording performance of discrete track patterned media fabricated by focused ion beam

We report on the recording performance of discrete track patterned media fabricated by focused ion beam (FIB). We investigated performance over a small area by spinstand read/write testing. Discrete track patterned regions show smaller magnetic track width and better signal separation between adjacent tracks and therefore higher track density than that of nonpatterned continuous media as a result of reduced side fringe effect and edge noise. We found that, at a designed groove depth of 4-8 nm, the shallow FIB etched grooves already provide good isolation between adjacent tracks, indicating the superiority of ion beam induced modification of magnetic properties in film media over physical modification of disk surface topography. This has implications for discrete track recording and media fabrication.

Design of a manufacturable discrete track recording medium

The potential benefits of patterning discrete tracks onto a disk for magnetic data storage have long been investigated. A practical process for manufacturing a cost-effective discrete track recording (DTR) medium has prevented such a disk from being introduced into a product. In this paper, a process utilizing nano-imprint lithography techniques to create a land and groove structure on the surface of a disk substrate will be described. Design considerations for the geometry of the structure, as well as of the magnetic write and read widths of the head, are discussed. Data showing the magnetic characteristics and recording performance of a DTR medium are also presented.

Discrete Tracks for Saturation Magnetic Recording

Discrete-track recording is a magnetic-recording method which employs a single-gap head and a discrete-track medium to increase the head-repositioning tolerance in saturation digital recording. A head with a conventional ring structure may be used. The recording medium consists of discrete magnetic tracks separated by nonmagnetic lands. Width of the magnetic tracks depends largely on the desired track density and maximum tolerable head-repositioning error. Test results indicate excellent track performance; consequently, satisfactory and reliable operation can be expected under actual machine conditions. Major advantages of discrete-track recording are economy, reliability, and increased head-repositioning tolerances.

Discrete tracks for saturation magnetic recording

Discrete-track recording is a magnetic-recording method which employs a single-gap head and a discrete-track medium to increase the head-repositioning tolerance in saturation digital recording. A head with a conventional ring structure may be used. The recording medium consists of discrete magnetic tracks separated by nonmagnetic lands. Width of the magnetic tracks depends largely on the desired track density and maximum tolerable head-repositioning error. Test results indicate excellent track performance; consequently, satisfactory and reliable operation can be expected under actual machine conditions. Major advantages of discrete-track recording are economy, reliability, and increased head-repositioning tolerances.