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Wave Access Bubble Domain Storage

IP.com Disclosure Number: IPCOM000050023D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 6 page(s) / 48K

Publishing Venue

IBM

Related People

Slonczewski, JC: AUTHOR

Abstract

This magnetic bubble domain storage uses propagation of data by wave motion in a lattice of magnetic bubble domains. Wave propagation of magnetic bubble wall oscillation in a bubble lattice is used to transmit data signals from the point of data input to any storage location, and from the storage location to the output sensor. Bubble translation is required but only over small distances. The storage cell is smaller than the limit of lithographic resolution required.

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Wave Access Bubble Domain Storage

This magnetic bubble domain storage uses propagation of data by wave motion in a lattice of magnetic bubble domains. Wave propagation of magnetic bubble wall oscillation in a bubble lattice is used to transmit data signals from the point of data input to any storage location, and from the storage location to the output sensor.

Bubble translation is required but only over small distances. The storage cell is smaller than the limit of lithographic resolution required.

Two magnetic bubble domain layers are used. One of these is the storage layer which contains a dense hexagonal lattice of unichiral bubbles that store wall-coded data and whose centers remain fixed in position. The radii of these bubbles are free to vibrate and thus to propagate waves for data transmission. These radial oscillations are sustained by currents in overlying conductors.

The other magnetic bubble domain layer is termed an index layer, and contains a smaller number of bubbles at great distances from one another. Each of these index bubbles will normally rest in a stable condition opposite one of the storage bubbles to whose datum access is desired. The index bubbles are moved about from one storage location to another with magnetic fields that can be generated by current-carrying lines. The device operates in a four-phase cycle including these phases: Phase 1 Index bubbles are moved to addressed locations.

Phase 2 Each storage bubble which is simultaneously coupled

to an index bubble and which carries a wall-coded

"1" state nucleates a radial oscillation disturbance

which expands laterally in its own channel or zone.

Phase 3 A shift register-like traveling-wave action causes

all of the radially oscillating zones to propagate

steadily in one direction. The vibrations of "read"

bits are sensed at one end, while new "write" bits

are introduced at the other end.

Phase 4 Each storage bubble which is simultaneously coupled

to an index bubble and located in a channel with a

vibrational "1" state switches its wall state from 0

to 1 or 1 to 0.

In more detail, Fig. 1 illustrates a cross-section of the magnetic garnet layers of the device. Fig. 2 shows a cross-section of the layers comprising the various drive conductors. The storage layer 10 is a garnet layer containing a regular hexagonal lattice of storage bubbles B. The two unichiral states in the storage bubbles, having right and left handed curling of wall moment, are used to designate binary 1 and 0, respectively. The position of the bubble lattice is determined by some form of mild periodic treatment, such as ion implantation, permalloy evaporation, etching, etc., through a mask.

A non-magnetic garnet spacer 12 is grown by either liquid phase epitaxy or chemical vapor deposition. An index-bubble layer 14 contains the index bubbles

1

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B(i). These bubbles are arranged on a periodic lattice, but are sufficiently far apart so that they are non-interacting. Their total nu...