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Dual Bubble Lattice File

IP.com Disclosure Number: IPCOM000083465D
Original Publication Date: 1975-May-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 6 page(s) / 93K

Publishing Venue

IBM

Related People

Argyle, BE: AUTHOR

Abstract

This bubble domain lattice file is a storage arrangement, in which magnetic bubble domains are held within an area of confinement in the bubble domain material. They are also located with respect to each other, such that their positions in the area of confinement are substantially determined by interactions between the bubble domains. In contrast with conventional overlay storage techniques where the position of each bubble domain is determined by the geometry of the overlay, no overlay pattern is used to define the bubble domain positions within the area of confinement.

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Dual Bubble Lattice File

This bubble domain lattice file is a storage arrangement, in which magnetic bubble domains are held within an area of confinement in the bubble domain material. They are also located with respect to each other, such that their positions in the area of confinement are substantially determined by interactions between the bubble domains. In contrast with conventional overlay storage techniques where the position of each bubble domain is determined by the geometry of the overlay, no overlay pattern is used to define the bubble domain positions within the area of confinement.

The bubble domains arrange themselves in a periodic array (lattice) and high density results, since the bubbles can be closely packed with respect to one another even in view of the interactions existing between the domains. This contrasts with conventional bubble domain apparatus, where bubble domains are spaced at least three or four bubble domain diameters from each other, in order to minimize interactions between adjacent bubble domains.

The bubble lattice file has been described in more detail at the Conference on Magnetism and Magnetic Materials, which occurred in December 1974 at San Francisco, California. Different types of schemes were presented for coding information in the lattice for representation of information.

It is proposed herein to code the lattice of bubble domains using dual-size bubble domains, such as are shown in Figs. 1A and 1B. These dual-size domains are designated A and B, where the A domain appears larger and/or taller than the B domain.

These domains can be converted to one another and can be generated as desired. However, if they are used to represent information in the bubble lattice file, the uniform bubble spacing which is necessary to provide a regular lattice would be difficult to achieve, since the spacing between individual bubble domains would have to be different throughout the lattice in order to accommodate the different size bubble domains. Therefore, the present technique uses pairs of A and B bubbles for representation of binary 1 and 0 bits. In this manner, the interbit spacing in the lattice is essentially uniform throughout the lattice.

Fig. 1A shows a top view of a bubble domain material, in which dual-size bubble domains A and B simultaneously exist in the same magnitude of bias field H(z). The bubble domain film is a composite film in which one layer has a magnetization M(1) and wall energy Sigma(1), while the other layer has magnetization M(2) and wall energy Sigma(2). As an example, 4 Pi M(1) = 320 gauss and 4 Pi M(2) = 265 gauss is suitable. In Fig. 1B, the dashed line representing the layered film need not be at the midplane of the bubble domain film. As an example, this layer 2 could be only 1/3 of the overall thickness of the bubble domain film.

Tables I and II designate the static behavior in one sample of isolated bubbles, and of homobubble lattices having the expected long-range p...