Browse Prior Art Database

Obtaining a Hard Magnetic Array in a Magnetically Soft Matrix

IP.com Disclosure Number: IPCOM000079845D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Berry, BS: AUTHOR [+2]

Abstract

A method of using the large difference in coercive force between an amorphous magnetic film and crystallized spots to fabricate a read-only memory is proposed. Such a memory can be switched off and on by reversing the applied magnetic field, with the information stored remaining constant.

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Obtaining a Hard Magnetic Array in a Magnetically Soft Matrix

A method of using the large difference in coercive force between an amorphous magnetic film and crystallized spots to fabricate a read-only memory is proposed. Such a memory can be switched off and on by reversing the applied magnetic field, with the information stored remaining constant.

Amorphous ferromagnetic alloy Fe(75)-P(15)-CrO is a magnetically soft material with a coercive force in the vicinity of 1 Oe. On the other hand, as shown above, crystallization of the amorphous alloy (by exposure to a temperature in excess of 450 degrees C) causes a transformation to a magnetically hard state with a coercivity of ~ 200 Oe. Despite the very large change in the coercivity, only a slight change is evident in saturation magnetization of the material. Such a material may be used as an information storage medium by the use of a laser or electron beam, to induce local recrystallized areas which define a "bit" of information. Although the memory would be a permanent one in the sense that the crystallized regions cannot be restored to the amorphous condition, the memory could be switched off by a magnetic field which magnetizes both hard and soft regions alike in the same direction. The information is, however, revealed by application of a reverse field of sufficient strength to reverse the magnetization of the soft regions, while not affecting the magnetization of the hard regions.

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