International Business Machines Corporation

Thomas R McGuire

Richard Joseph Gambino

Thomas S Plaskett

James M Harper

Jerome J Cuomo

Praveen Chaudhari

Joseph Adam Aboaf

Erik Klokholm

Michael W McElfresh

A method for forming a giant magnetoresistance sensor and method for making is described incorporating an oriented granular layer wherein the layer has a copper matrix with magnetic particles of a nickel cobalt alloy wherein the magnetic particles have a magnetocrystalline anisotropy constant K.sub.1 in the range from 0 to 3.times.10.sup.4 ergs/cm.sup.3. Alternatively, a silver or gold matrix may be used with magnetic particles of a nickel-iron alloy. The granular layer preferably has a (100) texture to provide the magnetic particles with their easy axes in the plane of the layer. The magnetic particles have their largest dimension in the range from 40 to 400 angstroms. The invention overcomes the problem of requiring a large magnetic field to obtain the saturation .DELTA.R/R. By providing a granular film with magnetic particles of low anisotropy, the saturation field to obtain .DELTA.R/R may be as low as 10 to 20 Oe.

Method of forming a giant magnetoresistance sensor

An amorphous alloy containing uranium and a member selected from the group of N, P, As, Sb, Bi, S, Se, Te, Po and mixtures thereof; and use thereof for storage medium, light modulator or optical isolator.

Amorphous uranium alloy and use thereof

A giant magnetoresistance sensor incorporating an orientated granular layer wherein the layer has a copper matrix with magnetic particles of a nickel cobalt alloy wherein the magnetic particles have a magnetocrystalline anisotropy constant K.sub.1 in the range from 0 to 3.times.10.sup.4 ergs/cm.sup.3. Alternatively, a silver or gold matrix may be used with magnetic particles of a nickel-ion alloy. The granular layer preferably has a (100) texture to provide the magnetic particles with their easy axes in the plane of the layer. The magnetic particles have their largest dimension in the range from 40 to 400 angstroms. The invention overcomes the problem of requiring a large magnetic field to obtain the saturation .DELTA.R/R. By providing a granular film with magnetic particles of low anisotropy, the saturation field to obtain .DELTA.R/R may be as low as 10 to 20 Oe.

Oriented granular giant magnetoresistance sensor

A magnetoresistive device is described for detecting magnetic fields incorporating a sandwich structure of four layers, two of which are ferromagnetic and which are separated by a non-ferromagnetic metallic layer and where one ferromagnetic layer is adjacent a fourth antiferromagnetic layer and exhibiting exchange anisotropy with the adjacent ferromagnetic layer. The invention overcomes the problem of small changes in magnetoresistance and in controlling the magnetization response of the magnetoresistive device.

Four layer magnetoresistance device and method for making a four layer

Devices and circuits are described employing magnetoresistive materials exhibiting a negative .DELTA..rho. effect (.DELTA..rho.=.rho..parallel.-.rho..perp.). In these materials, the electrical resistivity .rho. of the material in a direction perpendicular to the direction of current through the material is greater than the electrical resistivity .rho..parallel. of the material in a direction parallel to the direction of the electrical current through the material. These are ferromagnetic materials exhibiting magnetoresistance in the presence of an electrical current through the material and a magnetic field applied to the material to magnetize it to saturation at room temperature. These devices and circuits have advantages over conventional devices and circuits employing magnetoresistive materials of the conventional type, in which .DELTA..rho. is a positive quantity.

New magnetoresistive materials

A beam addressable file using as a storage medium an amorphous magnetic composition having uniaxial anisotropy. The storage medium can be prepared in thin film or bulk form or as particles in a binder. The storage medium can be comprised of a single element or a multicomponent system where at least one of the components has an unpaired spin so that the composition has a net magnetic moment. The storage comosition exists in a microcrystalline structure (i.e., it has localized atomic ordering over a distance 25-100 angstroms) and also in a substantially amorphous structure (i.e., when the composition has localized atomic ordering only over distances less than 25 angstroms). Binary and ternary compositions, either alloys or compounds, are suitable. particularly good examples are combinations of rare earth elements and transition metal elements. The magnetic properties of these amorphous magnetic compositions are easily changed during fabrication or after fabrication, and the compositions can be doped readily without adversely affecting magnetic properties. Either electron beams or light beams can be used to write information into the storage medium and optical readout is generally preferred. Curie point writing or compensation point writing is used.

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Yorktown Heights, NY, United States of America

Thomas R McGuire