Michael A. Russak

Grain size analysis of longitudinal thin film media

Magnetic layer grain size plays an important role in determining the materials properties of longitudinal magnetic thin film media. Therefore, accurate and appropriate microstructural analysis is crucial to understanding the effects of changes in sputtering parameters. In this work we introduce a cumulative percentage frequency plot that is superior in representing and comparing grain size distributions. The advantages of the cumulative method are demonstrated by discussing the outcome of applying a CoCr interlayer between the magnetic layer and the underlayer. Cumulative percentage frequency plots show that a log-normal distribution fits the grain size data best. In addition, applying an interlayer was found to result in improved magnetic properties.

Demonstration and characterization of 13 Gb/in/sup 2/ recording systems

We have successfully demonstrated recording at areal densities as high as 14.5 Gb/in/sup 2/ at data rates as high as 195 Mbit/s (24.4 MB/s) and at bit-aspect-ratios (BAR) as high as 14, using merged inductive-write/spin-valve-read heads on low noise thin film disks. Recording at a data rate of 300 Mbit/s (37.5 MB/s) has also been achieved at the corresponding linear density of 356 KBPI. Combining the areal density and data rate capabilities, the feasibility of recording at the capacity of 15.6 GB per 3.5 platter rotating at 5400 RPM, with the average data rate of about 240 Mbit/s (30 MB/s), has thus been demonstrated,.

Demonstration and characterization of greater than 60 Gb/in/sup 2/ recording systems

We have successfully demonstrated longitudinal recording at areal densities greater than 60 Gb/in/sup 2/ at data rates as high as 160 Mbps (20 MB/s) and at a Bit-Aspect-Ratio (BAR) of 5.7, using merged inductive-write/spin-valve-read heads with microactuators on low noise thin film disks. The heads were fabricated with standard photolithography and wafer pole trimming used in currently available commercial products. At track densities of 60 KTPI and higher, traditional servoing mechanisms are not adequate. With the use of a microactuator, we can further improve the track density by 15%, the linear density by 10% and the areal density by more than 20%. Thus, using a microactuator with the 50 Gb/in/sup 2/ head/media combination, we have increased our areal density achievement up to 63.2 Gb/in/sup 2/.

Demonstration and characterization of 36 Gb/in/sup 2/ recording systems

We have successfully demonstrated recording at areal densities as high as 36 Gb/in/sup 2/ at data rates as high as 173 Mbits/s (21.6 MB/s) and at a Bit-Aspect-Ratio (BAR) of 7.3, using merged inductive-write/spin-valve-read heads on low noise thin film disks. Recording at a data rate of 590 Mbits/s (73.8 MB/s) has also been achieved at the corresponding linear density of 231 KBPI. Comparisons with previous areal density demonstrations have also been summarized.

Magnetic and recording properties of CoCrPtTa thin film media with CrW underlayer

CoCrPtTa thin film media using Cr as an underlayer has been developed as a candidate for future high density longitudinal recording. In an effort to reduce the lattice mismatch between the Cr underlayer and the magnetic layer, the Cr underlayer has been doped with various elements. In this work the effect of adding Wx (x=10 and 15 at.u200a%) to the Cr underlayer on the magnetic, crystallographic, and recording properties are reported. CrW10(Cr90W10) underlayer produced about 400 Oe higher coercivity and higher S* at Mrt≈0.60u200amemu/cm2 compared to the Cr underlayer. Also at 240 kfci recording density for CoCrPtTa/CrW10 media the normalized media noise was similar and signal-to-noise ratio was about 2 dB higher compared to the CoCrPtTa/Cr media. For the CrW15(Cr85W15) underlayer at Mrt≈0.60u200amemu/cm2 the coercivity was about 300 Oe higher with S*=0.88, but the normalized media noise was also higher than the CoCrPtTa/Cr media. The x-ray diffraction data suggest better lattice match between the CoCrPtTa/CrW10 media...

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.

Process And Characterization Of Nitrogenated Carbon

Nitrogenated carbon films prepared in a DC-magnetron sputtering system were studied. Properties, including deposition rate, nitrogen content, nano-hardness, and thin film stress, were investigated as a function of deposition conditions, i.e. sputter power, substrate bias, substrate temperature, and sputter pressure.

26.5 Gb/in/sup 2/ areal-density longitudinal thin film media

A 26.5 Gb/in/sup 2/ areal-density demonstration was made using low-noise, thermally stable media and advanced dual-spin-valve heads. The demonstration was achieved at a linear density of 504 kbpi, a track density of 52.6 ktpi, and a data transfer rate of 230 Mb/s. The media had M/sub r/t of 0.40 memu/cm/sup 2/ and coercivity of 2500 Oe, and were composed of a dual-magnetic-layer structure with a five-element magnetic alloy. It was observed that smaller, uniform and isolated magnetic grains are critical to reducing the media noise and for designing ultra-high areal-density recording media that are thermally stable.

Effect of CrRu underlayer on the magnetic, recording, and thermal stability characteristics of CoCrPtTa thin film media

The effects of CrRu underlayers on the grain size, lattice matching, magnetic, recording and thermal stability characteristics for CoCrPtTa thin film media are presented, CrRu/sub 10/ and CrRu/sub 20/ underlayers produced about 800-960 Oe higher coercivity compared to media with a Cr underlayer. At 300 kfci recording density the CoCrPtTa/CrRu media has about 10-15% lower media noise and about 1-1.5 dB higher SNR compared to the similar media with Cr underlayer. X-ray diffraction data suggest somewhat better lattice matching between the CoCrPtTa/CrRu media due to the addition of Ru to the Cr underlayer compared to CoCrPtTa/Cr media. The CoCrPtTa/CrRu media has an average grain size of 12 nm in comparison to the average grain size of 15 nm for the CoCrPtTa/Cr media. The thin film media with CrRu/sub 10/ underlayer has smaller grain size but similar thermal stability performance compared to Cr underlayer.

Wear and corrosion resistance of thin overcoat with different interlayer materials

Several interlayer materials were introduced under a thin nitrogenated carbon film for corrosion and tribology evaluation. It was found that CrTa interlayer showed the best corrosion resistance but the worst wear performance, and amorphous carbon (a-C) and NiSi interlayers demonstrated reasonable wear resistance.