Areal-Density Capability Measurement Based on 747 Test in Magnetic Recording Systems
A method is presented for determining the areal density (AD) capability of a magnetic recording system based on a set of 747 tests taken over a range of linear densities. By fitting the measured results with a suitable functional form, we can readily predict off-track capability (OTC) at any combination of linear density and track density. Conversely, for a given OTC requirement, we can immediately find the maximum AD that can be reached and the bit aspect ratio required to achieve it. Our results also reveal the effect of skew angle on AD and match well with previous results for perpendicular magnetic recording.
Gigabit density recording using dual-element MR/Inductive heads on thin-film disks
Inductive-write and magnetoresistive (MR)-read dual-element heads of very narrow trackwidths and narrow gaps have been designed, fabricated, and recording-tested on thin-film media of high coercivity and squareness. Results show excellent writability at modest write currents of 50 mA, large readback amplitudes with good signal-to-noise performance, very high linear-density resolution up to 5000 fc/mm (-6-dB density), and trackwidths close to the design dimensions. These results show that such head-disk systems are capable of recording operations at a target areal density of 1 Gb/in/sup 2/. Another result is that novel techniques for measuring nonlinear transition shifts as well as offtrack and squeeze performance have been developed. >
Effect Of Track Edge Erasure And On-track Percolation On Media Noise At High Recording Density In Longitudinal Thin Film Media
In this work the experimental evidence of the effect of track edge erasure and on-track percolation on media noise is investigated using Magnetic Force Microscopy (MFM) for CoCrTaPt/Cr thin films deposited at different substrate temperatures (T/sub s/). As the recording density increases from 60 to 146 kfci, the track edges begin to erase and the effective track width reduces, causing a subsequent drop in the read back signal and increase in media noise. Also with the increase in recording density the bit length reduces and the transition boundaries get closer to each other. As a result, the transition boundaries are no longer sharp and show onset of percolation. The onset of on-track percolation for films deposited at 160/spl deg/C with higher exchange interaction occurs at lower recording density compared to the film deposited at 235/spl deg/C. The track edge percolation occurs at lower recording density than the on-track percolation for both samples.