International Business Machines Corporation

James K Howard

Richard H Ahlert

Cherngye Hwang

Michael Andrew Parker

James F White

Muhammad Inayet Ullah

Kevin Robert Coffey

Paul S Ho

Wei-Kan Chu

Richard Donald Umphress

Todd L Hylton

Robert Fontana

Daniele Mauri

Tsann Lin

Ian L Sanders

Steven E Lambert

Hung-Chang W Huang

Norbert Staud

Arup Bhattacharyya

Ching Hwa Tsang

Kris V Srikrishnan

Anthony W Wu

James Hsi-Tang Lee

Haralambos Lefakis

Amitava Gangulee

William D Rosenberg

Grace S Lim

Randall George Simmons

Robert Otto Schwenker

Robert J Miller

Pierre B Mollier

Kwang Kon Kim

Francis W Wiedman, Iii

Run-Han Wang

Tadashi Yogi

Wolfgang M Goubau

James C Uy

Frank E Turene

Dominique Basire

Mohammad T Moshref

Ting C Huang

Michael F Toney

Richard H Alhert

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 significantly thinner boron carbide overcoat layer is provided for a magnetic disk which has the same durability as thicker prior art overcoat layers for protecting an underlying magnetic layer. By employing adhesion layers selected from the group consisting of Ge, Ru, WTiSi, WTi, Si, and Y between the magnetic layer and the overcoat layer, the durability of the overcoat layer is significantly increased over a single overcoat layer of B4C. Certain process steps in the making of the B4C overcoat layer still further enhance the durability of the B4C overcoat layer by maintaining the disk or substrate specimen at a floating potential in a plasma chamber and employing low levels of argon pressure and sputtering wattage.

Method of making magnetic disk with boron carbide overcoat layer and

An alloy of tetragonal polycrystalline structure acts as a thin film magnetic medium. The medium can be for recording or sensing magnetic transitions representative of data and is of a thickness less than about 200 .ANG., and has a coercivity in excess of about 2000 Oe. The film is in the L1o phase which is suitable for longitudinal recording and can be constituted by an alloy selected from cobalt or iron together with platinum or palladium. The film is formed by sputtering from a target and thereafter annealing the thin film and at a temperature in excess of about 500.degree. C.

Thin film magnetic recording medium having high coercivity

Magnetic disk with boron carbide overcoat layer

A thin film lead structure resistant to resistance increase phenomenon resulting from contamination by mobile impurities. A thin film lead is disposed proximate to a getter layer material having a higher affinity for mobile impurities that the thin film lead. The getter layer material captures mobile impurities and prevents their migration into the thin film lead. The getter layer material may be formed over and in contact with the thin film lead, may be encapsulated within the thin film lead, or both. The getter layer material comprises a rare earth metal selected from the group consisting of yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, and ytterbium. The thin film lead is preferably tantalum, but may be selected from the group consisting of niobium, vanadium, chromium, molybdenum, tungsten and iron. An alternate embodiment of the invention includes a transition metal comprising titanium, zirconium, or hafnium as the getter layer. The capture of mobile impurities by the getter layer prevents resistance increase phenomenon and embrittlement to the thin film lead. The thin film lead may be used as a thin film lead to an electrical circuit, the sensor structure in a magnetic head.

Getter layer lead structure for eliminating resistance increase

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.

Multilayer magnetoresistive sensor

A magnetic disk storage system wherein a magnetic includes a magnetoresistive sensor is described. The MR sensor comprises a sputtered layer of ferromagnetic material and a sputtered layer of antiferromagnetic nickel-manganese (Ni-Mn) to provide an exchange coupled longitudinal bias field in the MR element. The antiferromagnetic layer overlays the MR layer and may be patterned to provide the longitudinal bias field only in the end regions of the MR layer. Alternatively, the antiferromagnetic layer can underlay the MR layer with a Zr underlayer to enhance the exchange-coupled field. As initially deposited, the Ni-Mn layer has a face-centered-cubic crystalline structure and exhibits little or no exchange-coupled field. After one annealing cycle at a relatively low temperature, the Ni-Mn layer crystalline structure is face-centered-tetragonal and exhibits increased crystallographic ordering and provides sufficient exchange coupling for the MR element to operate. Addition of chromium to the Ni-Mn alloy provides increased corrosion resistance.

Magnetoresistive sensor having antiferromagnetic exchange bias

A magnetic recording disk has an improved surface film formed on the disk blank. A sputter-deposited surface coating containing nickel, chromium and oxygen (Ni--Cr--O) is formed on a AlMg disk blank, after which a cobalt alloy magnetic layer is formed over the Ni--Cr--O coating and a protective overcoat is formed over magnetic layer. The use of the Ni--Cr--O coating on the disk blank eliminates the need for a wet electroless deposition process for creation of a surface coating and results in an inherent texturing of the subsequently deposited magnetic film and protective overcoat which conform to the surface texture of the sputter-deposited Ni--Cr--O. The disks made with the Ni--Cr--O surface film exhibit a very low static friction force between the air-bearing slider and the disk surface when the disks are used in contact start/stop (CSS) disk files.

Thin film magnetic recording disk comprising a metallic disk blank, a

A magnetoresistive (MR) sensor comprising a sputtered layer of ferromagnetic material and a sputtered layer of antiferromagnetic nickel-manganese (Ni-Mn) to provide an exchange coupled longitudinal bias field in the MR element is described. The antiferromagnetic layer overlays the MR layer and may be patterned to provide the longitudinal bias field only in the end regions of the MR layer. Alternatively, the antiferromagnetic layer can underlay the MR layer with a Zr underlayer to enhance the exchange-coupled field. As initially deposited, the Ni-Mn layer is face-centered-cubic and exhibits little or no exchange-coupled field. After one annealing cycle at a relatively low temperature, the Ni-Mn layer is face-centered-tetragonal and exhibits increased crystallographic ordering and provides sufficient exchange coupling for the MR element to operate. Addition of chromium to the Ni-Mn alloy provides increased corrosion resistance.

Method for fabricating a magnetoresistive sensor having

Magnetoresistive sensor having antiferromagnetic layer for exchange bias

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Morgan Hill, CA, United States of America

James K Howard