Changes in magnetic parameters due to annealing of the implanted epitaxial garnet-metal interface

Abstract

An aluminum-copper cover layer on implanted magnetic garnet causes a change in certain magnetic parameters, having a direct effect on the device parameters of a bubble memory chip. This change is NOT seen in nonimplanted garnet slices. After 2 h of annealing at 350 C in vacuum, there was a difference in bubble collapse field between the metal-covered garnet and the bare garnet. This difference in some cases was more than 10 Oe, and it was then simple to create a region depleted of bubbles surrounded by a region of densely packed bubbles. The depth of the interaction was 1300 Å, determined by successive ion-beam machining and collapse field measurements. This interaction depth was independent of the total annealing time. Since no aluminum has been detected in the garnet after anneals, an oxygen depletion mechanism is suggested.