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Staining Defects for Broad Area Inspection of Magnetic Bubble Domain Films

IP.com Disclosure Number: IPCOM000079067D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 27K

Publishing Venue

IBM

Related People

Argyle, BE: AUTHOR

Abstract

A device is described for inspecting magnetic bubble domain materials for defect density, i.e., number per square centimeter, and for distribution thereof according to the strength of magnetic bubble-to-defect interactions.

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Staining Defects for Broad Area Inspection of Magnetic Bubble Domain Films

A device is described for inspecting magnetic bubble domain materials for defect density, i.e., number per square centimeter, and for distribution thereof according to the strength of magnetic bubble-to-defect interactions.

Magnetically active defects can attract or repel magnetic bubbles and depending on the strength of the bubble-to-defect interaction, the defect may be deleterious to the operation of a given magnetic bubble domain device material. This device allows inspection of materials for the number per square centimeter of such defects, and aids in classifying such defects according to the strength and sign of the defect-to-bubble force, whether attractive or repulsive.

The magnetic force of a bubble moving translationally in the Y-direction in the plane of the film is given by the product of the field gradient, partial deriv. Hz/partial deriv. y, where z is directed normal to the film and the bubble diameter, which is assumed to be constant across the area being inspected. Such a field gradient is necessary to move the bubble against the defect force.

The use of bubble domains to stain defects is new. It can be shown that strip domains are not as sensitive to defects. Previous references citing the use of strips, do not claim anything about evaluating the strength of defect-to-bubble interactions. This arrangement allows photographic recording.

A pair of wires within the array shown in the figure, will generate a gradient at the midpoint of the pair partial deriv. of Hz over part. deriv. of y = 1.6 I/d/2/ X = 0 or at the plane of the film located a distance X below the plane of the array of wires, according to the general case

(Image Omitted)

Thus, if the defect can be found and centered between a pair of wires, the force expressible as a field, H , between the bubble and the defect can be measured according to H(f) = partial deriv. of Hz over partial deriv. of y x D where D is the diameter of the bubble.

The...