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DUAL/DIFFERENTIAL GMR SENSOR USING GRANULAR FILMS

IP.com Disclosure Number: IPCOM000013875D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2003-Jun-18

Publishing Venue

IBM

Abstract

Granular GMR films of CoCu, CoAg are known to exhibit high values of magnetoresistance for Co concentration near 30 at.%. However, these films also exhibit very large switching fields due to high magnetic anisotropy and large magnetic coupling between the grains. We disclose that it is possible to reduce the switching field by using composite layer sensor, e.g., CoCu/NiFeX where NiFeX is a high resistivity and magnetically soft alloy. A dual/differential GMR head has following structure: CoCu/NiFeX/Al2O3/NiFeX/CoCu Al2O3 serves as the insulating gap between the two sensors. The sense current flowing through the sensor layers biases each sensor so that the ouput signals from the sensors can be added using the differential detection. 1