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GMR Head Free Layer Composition Specification For Higher Magnetic Stability Disclosure Number: IPCOM000014167D
Original Publication Date: 2000-Dec-01
Included in the Prior Art Database: 2003-Jun-19

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Net magnetostriction constant for Co90Fe10/Ni82Fe18 composite film, less than 60 A thick, is positive. This leads to very high magnetic instability (Kinks/Jumps) in the sensor response resulting in very wide distribution for the read back signal asymmetry for the GMR heads. Experimental data shows that higher "Ni" content Free layer, Co90Fe10/Ni83Fe17, thickness about 40 A leads to much improvement in magnetic stability, noticeable reduction in Kinks/Jumps in the sensor response. This improvement in magnetic stability is linked to negative magnetostriction constant for the Free layer due to use of "Ni" rich NiFe. It is expected that as Free layer thickness decreases, further adjustment of composition will be needed to maintain low negative magnetostriction constant for higher magnetic stability. 1