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High-Density Mass Storage Memories for Knowledge and Information Storage

Cel

The objective of project 957 was to develop vertical and magnetooptical recording technologies for mass storage on rotating discs. Compared with classical recording techniques, these technologies are potentially capable of providing much higher storage d ensities, as well as higher storage reliability and more competitive storage costs.
The objective of project 957 was to develop vertical and magnetooptical recording technologies for mass storage on rotating discs. Compared with classical recording techniques, these technologies are potentially capable of providing much higher storage densities, as well as higher storage densities, as well as higher storage reliability and more competitive storage costs.

Vertical recording technology was investigated and developed for both floppy and rigid discs. Addressed topics included media and substrates and read/write heads. A new optical pick up was designed for magnetooptical recording. In addition to the development of basic components and technologies, work was carried out for simulation of the mechanical dynamics of flying heads. The specific technical objectives achieved in the case of vertical recording were a linear density of 40000 fci and a radial density of 1500 tpi for rigid discs. The magnetooptical system should provide a linear density of 20000 bpi and a radial density of 10000 tpi. In terms of the capacities, these results for 5.25 inch drives correspond to 150 to 200 MB for vertical rigid discs, and 400 to 500 MB for magnetooptical discs.
Vertical recording technology was investigated and developed for both floppy and rigid discs. Addressed topics included media and substrates and read/write heads. A new optical pickup was designed for magneto-optical recording. In addition to the develop ment of basic components and technologies, work was carried out for simulation of the mechanical dynamics of flying heads.
The specific technical objectives achieved in the case of vertical recording were a linear density of 40000fci and a radial density of 1500tpi for rigid discs. The magneto-optical system should provide a linear density of 20000bpi and a radial density of 10000tpi. In terms of the capacities, these results for 5.25"drives correspond to 150 to 200MB for vertical rigid discs, and 400 to 500MB for magneto-optical discs. The project was divided into four tasks:
-Floppy Discs
Problems linked to CrCo tribology at high linear densities in perpendicular recording were encountered, but could not be satisfactorily solved from an industrial point of view. Even with a carbon upper layer, the head-media interface still poses major pr oblems which induce a lifetime far below the expected values. Studies on BaFe were therefore emphasised during the last year, both on material preparation and on coating technologies. Powders made by BASF made it possible to achieve media characteristics at the best worldwide level and will lead to commercial products as soon as the market is developed.
-Rigid Discs
Optimisation of composition for the media was reached. A new sublayer was developed and the intermediate layer was studied. Glass substrates showed excellent mechanical and structural characteristics. Recording with a linear density up to 40Kfci was successfully done with magnetic heads which are available in the market place. Improvements are still needed on the studied thin film heads to increase the recording density on these discs from 20to40fci.
The optimisation of the RF sputtering deposition conditions for CrCo films also led to the realisation of layers adapted for magneto printers.
-Magneto-Optical Media and Heads
Work was carried out on media (garnets and amorphous Rare Earth Transition Metal (RETM) alloys) and pickup systems.
Amorphous RETM alloys films were shown to have suitable properties as storage media but to exhibit ageing when the media were stored in a wet atmosphere. Optimum deposition conditions (especially argon pressure) improve the ageing of the layer through acontrol of its microstructure.
Thin garnet films are thought to be possible competitors to RETM alloys, especially if they can be deposited by sputtering. Moreover, the combination of a magnetooptical garnet film for read-out and of a ferrite film for the storage of the information looks very promising. Garnet films obtained by facing target sputtering need to be improved by focusing on the sputtering conditions.
Optical components for a pickup system based on a new original concept were developed and tested. A complete mock-up was built with the integrated read-out and write functions, and was tested with respect to noise sources and defects.
-Simulation
Specification of the head interface was completed, and software tools for testing different coding schemes were developed.
Exploitation
The three major objectives of this project (vertical magnetic recording for achieving extremely high storage densities, reversible optical recording, and the magneto-optical technology to achieve extremely high surface densities) are currently considered worldwide as strategic targets, and hence their achievement put the partners in a strong competitive position.
Some of the results pave the way for industrial products in the near future (such as BaFe floppy discs). The other results, especially on magneto-optical discs and heads, give the partners a strong background, which is being applied in ESPRITproject 2013 on magneto-optical disc drives.

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Koordynator

Bull SA
Wkład UE
Brak danych
Adres
48 rue Jean Jaures
78340 Les-Clayes-Sous-Bois
Francja

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