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Generation of Bubble Domain Through Exchange Coupling

IP.com Disclosure Number: IPCOM000078562D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Hayashi, N: AUTHOR

Abstract

It has been reported by T.W. Liu et al, in an article entitled "Thin Film Surface Bias on Magnetic Bubble Materials", J. Appl. Phys., 42, 1360-1361 (1971), that a kind of domain wall (to be called pseudowall hereafter) exists at the interface between a platelet of Sm(0.55)Tb(0.45/-/) orthoferrite and a thin layer of hard magnetic material, Co(5/-/) rare earth sputtered thereon. By making use of this pseudowall, a method of magnetic bubble generation is possible.

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Generation of Bubble Domain Through Exchange Coupling

It has been reported by T.W. Liu et al, in an article entitled "Thin Film Surface Bias on Magnetic Bubble Materials", J. Appl. Phys., 42, 1360-1361 (1971), that a kind of domain wall (to be called pseudowall hereafter) exists at the interface between a platelet of Sm(0.55)Tb(0.45/-/) orthoferrite and a thin layer of hard magnetic material, Co(5/-/) rare earth sputtered thereon. By making use of this pseudowall, a method of magnetic bubble generation is possible.

For a perfect, defectless uniaxial bubble medium, a nucleation field is needed equal to the anisotropy field H(k) of the material. Since H(k) is much greater than 4 pi M(s) for typical bubble materials, it appears impossible to nucleate a bubble domain with external field less than 4 pi M(s), unless some measures are taken to lower H(k). The essence of the present proposal is to move the pseudowall into the bubble medium, in order to create a bubble domain under a local field less than 4 pi M(s). unless, physically, the mode of "nucleation" considered here is not really nucleation but a kind of wall motion. The reasoning of the present conjecture is based on widely observed empirical fact, that to move an existing domain wall is easier than to reverse magnetization by "true" nucleation process.

Fig. 1 illustrates a simplified "nucleation" process by pseudowall motion. A localized field Ha(r) (from an appropriate current loop or some other devices) and ...