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High Density Bubble Domain Memory

IP.com Disclosure Number: IPCOM000074287D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Keefe, GE: AUTHOR [+2]

Abstract

Cylindrical magnetic domains can be propagated in orthoferrite material and memory functions are possible. The propagation means employed is usually conductor circuitry or permalloy patterns located on the surface of the orthoferrite. However, the magnetic fields produced by these propagation means decay rather slowly along a direction normal to the platelet surface, thus establishing a lower limit on the spacing between adjacent orthoferrite platelets.

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High Density Bubble Domain Memory

Cylindrical magnetic domains can be propagated in orthoferrite material and memory functions are possible. The propagation means employed is usually conductor circuitry or permalloy patterns located on the surface of the orthoferrite. However, the magnetic fields produced by these propagation means decay rather slowly along a direction normal to the platelet surface, thus establishing a lower limit on the spacing between adjacent orthoferrite platelets.

In order to increase the packing density of orthoferrite platelets, a high- permeability magnetic sheet is inserted between adjacent memory planes (platelets) to shield this stray magnetic field. The high-permeability materials can be permalloy or ferrite, for example. To prevent the magnetic field from penetrating into adjacent memory planes yet without decreasing the magnetic field strength for propagation, the high-permeability layer should be equally spaced from the propagation means located on adjacent memory planes. This spacing is chosen to be comparable to the length of the permalloy bars used in the propagation means. For instance, if the permalloy bar length in a memory plane is 0.5 mils, a keeper sheet used between memory planes spaced 2 mils will avoid coupling between memory planes. In this arrangement, the density of the memory planes can be increased by a factor of about 35.

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