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Reduction of K(1) in Bubble Domain Films

IP.com Disclosure Number: IPCOM000089630D
Original Publication Date: 1977-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Cronemeyer, DC: AUTHOR [+3]

Abstract

In bubble domain devices made on (111) and (100) substrates, a large magnetocrystalline anisotropy energy K(1) causes bubbles to hang up in certain crystallographic directions related to the traces of [111] directions on the plane of the film. The effect is especially annoying when K(1) and K(u) are of the same order of magnitude, and a rotating drive field is employed to circulate the bubbles. Often the bubbles fall out of step with the drive field rotation, causing failure of operation of the device.

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Reduction of K(1) in Bubble Domain Films

In bubble domain devices made on (111) and (100) substrates, a large magnetocrystalline anisotropy energy K(1) causes bubbles to hang up in certain crystallographic directions related to the traces of [111] directions on the plane of the film. The effect is especially annoying when K(1) and K(u) are of the same order of magnitude, and a rotating drive field is employed to circulate the bubbles. Often the bubbles fall out of step with the drive field rotation, causing failure of operation of the device.

The magnetocrystalline anisotropy coefficient K(1) can be drastically changed by addition of Pb to members of the Eu:YIG composition system. In the case of EuIG on (111) substrates, the room temperature value of K(1) with no Pb is - 34,000 ergs/cm/3/ and is decreased in magnitude by about 30% to -22,000 by an addition of 6 wt. % Pb. In the case of (111) Eu(2)Y(1)IG, almost as large a change is found -- a decrease of 29% by an addition of 6 wt. % Pb. (In the cases of (111) Eu(1)Y(2)IG and YIG, an opposite effect is found, but these are of no interest for bubble domain applications since q is much too low). Even larger effects are observed in the (100) system.

The large magnitude of the K(1) reduction by Pb is unexpected on the basis of dilution of the Eu's, and it opens up the following interesting new possibilities:
(1) The magnitude of K(1) can be driven down, and at the same time K(u) has been previously shown to be driven...