Bull S.a.

Jean-Claude Bouchand

Jacques Desserre

Dominque Jeanniot

A substrate for perpendicular anisotropic magnetic recording comprises a nonmagnetic substrate (SUBSI) on which a thin metal magnetic medium (CMI) having a negative magnetostrictive effect is deposited. The direction of easy magnetization of the medium is perpendicular to the surface. In order to minimize the magnetostrictive effect in the metal magnetic medium, the medium comprises a stack of alternate thin magnetic and nonmagnetic layers (CI.sub.1 -CI.sub.n, ISO.sub.1 -ISO.sub.n-1), the nonmagnetic layers (ISO.sub.1 -ISO.sub.n-1) being sufficiently flexible so as to dampen the effect of the strains in the magnetic layers and enable strong magnetic coupling between them. The thickness of the nonmagnetic layers is between 150 and 250 angstroms, while the thickness of the magnetic layers is between 700 and 2000 angstroms. The stack may include as many as 10 or more magnetic layers of a chrome/cobalt alloy. The nonmagnetic layers may be SiO, SiO.sub.2 and mixtures thereof. The invention is applicable to magnetic recording disks.

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Beynes, France

Jean-Claude Bouchand