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Laminated Structures for Bubble Domain Devices

IP.com Disclosure Number: IPCOM000078559D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hendel, RJ: AUTHOR [+4]

Abstract

Among the three techniques for bubble domain propagation, a permalloy bar is most commonly used because of its simplicity for fabrication and operation. To propagate bubble domains efficiently, the permalloy bar should not only produce maximum pole strength, but also respond to the in-plane field fast enough so that the device data rate is not limited by the switching speed of the permalloy circuits.

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Laminated Structures for Bubble Domain Devices

Among the three techniques for bubble domain propagation, a permalloy bar is most commonly used because of its simplicity for fabrication and operation. To propagate bubble domains efficiently, the permalloy bar should not only produce maximum pole strength, but also respond to the in-plane field fast enough so that the device data rate is not limited by the switching speed of the permalloy circuits.

Domain patterns observed in regular permalloy circuits by Bitter techniques indicate that "closure domains" are prevalent, because of the nature of open-flux structures. "Domain growth" instead of "rotation" is responsible for magnetization reversal. The in-plane field required to wipe out the walls is around the self- demagnetizing field, which is considerably larger than the practical value of in- plane drive.

This implies that the response of permalloy circuits to in-plane field is through rather slow (mu sigma) magnetization rotations. Therefore, in addition to the bubble response time to permalloy circuits, the permalloy circuit response time to in-plane field may become another limiting factor of device data rate. This is particularly evident in bubble domain generators, in which significant amount of time is required for domain wall to move from the center of the generator toward the end.

Laminated permalloy circuits are suggested, which consist of a thin- nonmagnetic layer (e.g. 300 angstroms Cu or Au) sandwiched...