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Exchange Coupled Magnetic Recording Structure

IP.com Disclosure Number: IPCOM000085328D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Missel, L: AUTHOR [+2]

Abstract

A problem in magnetic recording media is obtaining a good magnetic layer while preventing corrosion. Thick protective coatings of precious metals are generally employed to protect the magnetic layer. However, these protective coatings are generally nonmagnetic and, therefore, require that the transducer sensing the magnetic flux transitions be spaced yet a further distance from the media. The transducer generally has a film of air between it and the media, and this together with the protective coating limits the density of the magnetic transitions that can be recorded.

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Exchange Coupled Magnetic Recording Structure

A problem in magnetic recording media is obtaining a good magnetic layer while preventing corrosion. Thick protective coatings of precious metals are generally employed to protect the magnetic layer. However, these protective coatings are generally nonmagnetic and, therefore, require that the transducer sensing the magnetic flux transitions be spaced yet a further distance from the media. The transducer generally has a film of air between it and the media, and this together with the protective coating limits the density of the magnetic transitions that can be recorded.

To solve this problem, the protective layer shown in the figure is a ferromagnetic layer exchange coupled to the main magnetic layer underneath. The resultant coercivity of the combined layer is less that the magnetic layer, but is higher than the protective layer.

The protective layer can be a ferromagnetic or ferrimagnetic material. The only requirement is that this layer be capable of being exchange coupled to the magnetic layer. The protective layer must also be noncorrosive so as not to pit or corrode and cause asperities that contact the transducer and can produce head crashes. The coercivity of the protective layer is of little importance, since the resultant magnetic properties of the two layers is sensed by the transducer.

The magnetic layer likewise can be any ferromagnetic material having a high coercivity. A representative figure is equal to...