Magnetic Peripherals Inc.

Rajiv Y Ranjan

David N Lambeth

Jodie A Christner

A magnetic thin film recording medium is provided for longitudinal recording of magnetic flux transitions, with the read-back signals enhanced due to a substantial reduction in media noise. The reduced noise level is the result of a unique vacuum deposition process for applying an underlayer to a substrate, prior to deposition of the magnetic thin film. In particular, the underlayer is deposited in a low temperature plasma process under increased pressure of argon or another inert gas and at reduced deposition rates, thus to create voids or interstitial areas which substantially isolate individual grains from their neighboring grains. The subsequently deposited magnetic thin film replicates the crystalline structure and orientation of the chromium underlayer, for relatively isolated grains in the recording layer. This results in lower media noise levels, approaching or equalling those characteristic of particulate media.

Low noise magnetic thin film longitudinal media

Magnetic recording media are controllably textured, particularly over areas designated for contact with data transducing heads. In connection with rigid media, the process includes polishing an aluminum nickel-phosphorous substrate to a specular finish, then rotating the disc while directing pulsed laser energy over a limited portion of the radius, thus forming an annular head contact band while leaving the remainder of the surface specular. The band is formed of multiple individual laser spots, each with a center depression surrounded by a substantially circular raised rim. The depth of the depressions and height of the rims are controlled primarily by laser power and firing pulse duration. The shape of individual laser spots can be altered by varying the laser beam inclination relative to the disc surface. On a larger scale, the frequency of firing the laser in combination with disc rotational speed controls the pattern or arrangement of laser spots. The smooth, rounded contours of the depressions and surrounding rims, as compared to the acicular character of mechanically textured surfaces, is a primary factor contributing to substantially increased durability of laser textured media.

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Edina, MN, United States of America

Rajiv Y Ranjan