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Magnetoresistive Sensing of Micron Sized Bubble Domains Through Push Pull Operation of Bridge Detector Pairs

IP.com Disclosure Number: IPCOM000080499D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Almasi, GS: AUTHOR [+2]

Abstract

The bridge structure shown for sensing magnetic bubble domains is an improvement of that shown in U. S. 3,736,419. A magnetic bubble domain sheet 10 has located adjacent to it a bridge sensor generally designated 12. This bridge sensor includes an active magnetoresistive detector 14A and a dummy magnetoresistive detector 14B, and a conductor 16. Permalloy propagation elements, such as T bars 18T and I bar 18I are used to move domains in magnetic sheet 10, in a manner well known.

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Magnetoresistive Sensing of Micron Sized Bubble Domains Through Push Pull Operation of Bridge Detector Pairs

The bridge structure shown for sensing magnetic bubble domains is an improvement of that shown in U. S. 3,736,419. A magnetic bubble domain sheet 10 has located adjacent to it a bridge sensor generally designated 12. This bridge sensor includes an active magnetoresistive detector 14A and a dummy magnetoresistive detector 14B, and a conductor 16. Permalloy propagation elements, such as T bars 18T and I bar 18I are used to move domains in magnetic sheet 10, in a manner well known.

Only the active detector 14A is in proximity to the path of the bubble domain BD. This arrangement leads to DC level and noise cancellation, where the noise is that due to the response of the individual detectors 14A and 14B to the in- plane magnetic propagation field H. When the domain BD is propagated past the detector 14A, the magnetoresistive output of the active detector is reduced, since the bubble domain field is 180 degrees out of phase with the propagation field when the bubble domain is located at pole position 4 of permalloy element 18I. This causes a bridge unbalance and a resulting sense signal.

However, the sense signal is actually from the dummy detector 14B and, if its output could be increased in the presence of a bubble domain on the active detector, a higher net sense signal can be obtained. In this structure, a bubble BD located at pole position 4 of element 18I...