Dynamic magnetic information storage or retrieval – Head – Hall effect
Patent
1993-10-15
1995-04-18
Levy, Stuart S.
Dynamic magnetic information storage or retrieval
Head
Hall effect
338 32R, 324252, G11B 5127, G11B 533
Patent
active
054083770
ABSTRACT:
A magnetic recording data storage system of high recording density is made possible by an improved magnetoresistive sensor. The sensor has a ferromagnetic sensing layer that is a laminated layer of two ferromagnetic films antiferromagnetically coupled to one another and separated by an antiferromagnetically coupling film. By appropriate selection of the thickness of the nonmagnetic antiferromagnetically coupling film, the ferromagnetic films become antiferromagnetically coupled and their magnetizations rotate as a single rigid unit in the presence of the external magnetic field to be sensed. The ferromagnetic sensing layer can be used in conventional magnetoresistive sensors of the anisotropic magnetoresistive (AMR) type and in spin valve magnetoresistive (SVMR) sensors. In the spin valve sensor, the laminated ferromagnetic sensing layer serves as the free layer and is preferably formed of two films of nickel-iron (Ni-Fe) separated by a ruthenium (Ru) antiferromagnetically coupling film. Because the two ferromagnetic films have their moments aligned antiparallel, then, assuming the two films are made of the same material, by selecting the two films to have different thicknesses the effective free layer thickness can be reduced without significantly reducing the magnetoresistance.
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Gurney Bruce A.
Lefakis Haralambos
Need, III Omar U.
Parkin Stuart S. P.
Speriosu Virgil S.
Berthold Thomas R.
International Business Machines - Corporation
Klimowicz William J.
Levy Stuart S.
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