International Business Machines Corporation

Todd L Hylton

James K Howard

Michael Andrew Parker

Kevin Robert Coffey

Robert Fontana

Ching Hwa Tsang

Richard H Ahlert

Muhammad Inayet Ullah

Richard Donald Umphress

A heterogeneous thin film structure including a discontinuous layer of ferromagnetic material deposited on an insulating substrate and overcoated with a layer of nonmagnetic electrically conductive material exhibits giant magnetoresistance in saturation fields on the order of 350 Oersteds. A layer of ferromagnetic material is deposited on a heated insulating substrate by high vacuum evaporation techniques to form a layer of isolated ferromagnetic particles and overcoated with a nonmagnetic conductive material to form a plurality of ferromagnetic particles embedded in a nonmagnetic conductive matrix. As the ferromagnetic and nonmagnetic materials are deposited separately, it is not required that the two materials be immiscible and subsequent annealing is not required to induce phase separation.

Magnetoresistive sensor utilizing a granular magnetoresistive layer

A magnetic encoder apparatus for determining the position of a moving object. The encoder has a merged magnetoresistive (MR) head capable of maintaining a magnetic transducing relationship with a magnetic medium on a substrate while there is relative motion between the head and the medium. The merged MR head contains an MR read element and an inductive transducer write element. The inductive transducer write element is capable of writing encoded bits that contain information that defines a position of the substrate. The MR read element is capable of reading these encoded bits and generating an output signal. The output signal is processed by electronic circuitry in order to decipher the position of the moving object that is coupled with the encoder.

Magnetic recorder having MR read and inductive write capability

A high-density recording media comprising longitudinally oriented polycrystalline barium ferrite exhibits large coercivity, corrosion resistance, high hardness and durability. Films are prepared by on-axis sputtering at ambient temperatures from stoichiometric targets followed by a post-deposition anneal at approximately 850.degree.C. to induce crystallization. Crystallization yields a magnetic film with large in-plane remanence and a fine scale texturing that greatly improves the tribological performance of barium ferrite disks. Exceptional durability can be achieved on disks without overcoats. Grain sizes as small as 200 .ANG. are produced by doping with small amounts of Cr.sub.2 O.sub.3 or other additives. Coercivities greater than 4000 Oe are achieved even in small grain films.

Barium ferrite thin film for longitudinal recording

A magnetoresistive read sensor incorporates a granular multilayer sensing element comprising a plurality of layers of generally flat particles of a ferromagnetic material embedded in a nonmagnetic electrically conductive material. A bias layer separated from the magnetoresistive sensing element by a spacer layer provides a magnetic field to bias the magnetoresistive sensing element at a desired non-signal point. The ferromagnetic and the nonmagnetic materials are mutually immiscible, or may be miscible or partially miscible and processed in a manner to control interdiffusion. The magnetoresistive sensing element is formed by alternatively despositing layers of ferromagnetic material and layers of nonmagnetic conductive material on a substrate and then annealing the structure. During the annealing cycle, the layers of nonmagnetic material above and below the ferromagnetic layers penetrate at grain boundaries and break the continuity of the ferromagnetic layers to form layers or planes of ferromagnetic particles embedded in a matrix of nonmagnetic material.

Method for manufacturing granular multilayer mangetoresistive sensor

A magnetoresistive read sensor incorporates a multilayer sensing element formed of one or more magnetoresistive elements in a planar array, each magnetoresistive element having a multilayer structure of at least two ferromagnetic layers separated by a nonmagnetic layer. The ferromagnetic layers are coupled antiferromagnetically by magnetostatic coupling at opposing edges of the ferromagnetic layers. A bias layer separated from the magnetoresistive sensing element by a spacer layer provides a magnetic field to bias the magnetoresistive sensing element at a desired non-signal point for linear response. The magnetoresistive sensing element is formed by alternatively depositing layers of ferromagnetic material and layers of nonmagnetic material on a substrate and then patterning the resulting structure using photolithographic techniques to provide a planar array of magnetoresistive elements. A conductive layer is deposited over the array filling in the spaces separating the magnetoresistive elements to provide electrical conductivity between the elements in the plane of the structure.

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San Jose, CA, United States of America

Todd L Hylton