Magnetic magneto-optical disk

Magneto-optical disks (MODs) are rewritable, and operate differently than either ROM or WORM disks. Data is not recorded as distortions of a thermally sensitive layer within the disk. Rather, it is written using combined magnetic and optical techniques. Digital data consisting of Is and Os is encoded in the optical signal from the laser in the usual manner. Unlike the ROM or WORM disks, however, the MOD write layer is magnetically sensitive. 

Another example is the discovery of the rare earth metals (REM), seventeen in number. It started at the turn of the century 1800 in two small Swedish villages, Yt-terby in the archipelago of Stockholm and Bastnoes in the province of Vestmanland. For a long time these metals, with their curious names, dysprosium, samarium, ytterbium. .., were of only academic interest Today the rare earth metals attract worldwide technical interest for many advanced apphcations, e.g. batteries, magnets, lasers, fiber optics, RE-doped semiconductors, magneto-optical disks, superconductors and... 

In magneto-optical disks, Si3N4 and AIN films produced by sputtering are applied to protect against oxidation of the magnetic layer and enhance the magnetic Kerr rotation angle. 

The critical metallic components of advanced magnetic and magneto-optic (MO) storage devices— thin-film metal disks, inductive or magnetoresistive heads, and MO layers—are all susceptible to corrosion and each has been a subject of considerable study. Several review articles covering corrosion of magnetic-storage media may be found in the literature [135,136]. 

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