International Business Machines Corporation

Ronald Franklin Marks

Robin Frederick Farrow

Bruce Alvin Gurney

David Darden Chambliss

Matthew Joseph Carey

David Thomas Margulies

Hoa Van Do

Philip M Rice

Ren Xu

Robin Frederick Charles Farrow

Eric Dean Tober

Peter Alfred Gruber

Daniele Mauri

Edwin Joseph Selker

Jerry M Woodall

Steven Lorenz Wright

Arthur R Zingher

David James Frank

Stuart Stephen Parkin

Peter Daniel Kirchner

Ephraim Bemis Flint

George D Pettit

Graham Olive

An exchange-coupled magnetic structure of a cobalt-ferrite layer adjacent a magnetic metal layer is used in magnetorestive sensors, such as spin valves or tunnel junction valves. The exchange-coupled magnetic structure is used in a pinning structure pinning the magnetization of a ferromagnetic pinned layer, or in an AP pinned layer. A low coercivity ferrite may be used in an AP free layer. Cobalt-ferrite layers may be formed by co-sputtering of Co and Fe in an oxygen/argon gas mixture, or by sputtering of a CoFecomposition target in an oxygen/argon gas mixture. Alternatively, the cobalt-ferrite layer may be formed by evaporation of Co and Fe from an alloy source or separate sources along with a flux of oxygen atoms from a RF oxygen atom beam source. Magnetoresistive sensors including cobalt-ferrite layers have small read gaps and produce large signals with high efficiency.

Method for making a magnetoresistive sensor having a cobalt-ferrite pinning layer

An exchange-coupled magnetic structure of a cobalt-ferrite layer adjacent a magnetic metal layer is used in magnetorestive sensors, such as spin valves or tunnel junction valves. The exchange-coupled magnetic structure is used in a pinning structure pinning the magnetization of a ferromagnetic pinned layer, or in an AP pinned layer. A low coercivity ferrite may be used in an AP free layer. Cobalt-ferrite layers may be formed by co-sputtering of Co and Fe in an oxygen/argon gas mixture, or by sputtering of a CoFe composition target in an oxygen/argon gas mixture. Alternatively, the cobalt-ferrite layer may be formed by evaporation of Co and Fe from an alloy source or separate sources along with a flux of oxygen atoms from a RF oxygen atom beam source. Magnetoresistive sensors including cobalt-ferrite layers have small read gaps and produce large signals with high efficiency.

Spin valves with co-ferrite pinning layer

A magnetoresistive sensor for use as the read sensor in magnetic recording disk drives uses a permalloy (approximate composition of Ni.sub.81,Fe.sub.19) sensor layer with a magnetoresistance coefficient significantly greater than prior art permalloy sensor layers for a range of permalloy film thicknesses. The permalloy film is deposited on a substrate, such as alumina, that is essentially non-reactive with permalloy at elevated temperatures while the substrate is heated. The permalloy films have a zero or slightly negative magnetostriction, low easy and hard axis coercivities, and a low anisotropy field. At very small film thicknesses the permalloy films formed with substrate heating exhibit an even greater percentage increase in magnetoresistance coefficient than at higher film thicknesses, thereby allowing the films to function in magnetic recording disk drive heads for use at very high linear recording densities. The precise composition of the Ni--Fe alloy forming the sensor layer can be varied slightly, depending on the film thickness, to provide a sensor layer with essentially zero or slightly negative magnetostriction.

Magnetoresistive magnetic recording head with permalloy sensor layer

A magnetoresistive sensor based on a giant magnetoresistance multilayer uses a multilayer structure formed of alternating layers or stripes of ferromagnetic and nonferromagnetic metal that are spontaneously formed or 'self-assembled' laterally on a special template layer. The template layer is a crystalline structure that has a two-fold uniaxial surface, i.e., one that is structurally invariant for a rotation by 180 degrees (and only 180 degrees) about an axis (the symmetry axis) perpendicular to the surface plane. Such a template layer is the (110) surface plane of body-centered-cubic Mo. The alternating stripes of ferromagnetic metal (such as Co or Fe) and nonferromagnetic metal (such as Ag) become spontaneously arranged laterally on the template layer during co-deposition, such as during ultrahigh vaccum evaporation, and are aligned so that the direction of composition modulation, i.e., the direction perpendicular to the alternating stripes is along one of the unique axes of the template layer and in a plane parallel to the template layer. A crystalline base layer may be used beneath the template layer to enhance the growth of the template layer. If the template layer is (110) Mo, then the base layer may be sapphire having its (1 1 2bar 0) plane parallel to the (110) Mo plane.

Self-assembled giant magnetoresistance lateral multilayer for a

A method for forming a magnetoresistive sensor results in the spontaneous formation or 'self-assembly' of a giant magnetoresistance multilayer structure of alternating stripes of ferromagnetic and nonferromagnetic metal that are stacked laterally on a special template layer. The template layer is a crystalline structure that has a two-fold uniaxial surface, i.e., one that is structurally invariant for a rotation by 180 degrees (and only 180 degrees) about an axis (the symmetry axis) perpendicular to the surface plane. Such a template layer is the (110) surface plane of body-centered-cubic Mo. The alternating stripes of ferromagnetic metal (such as Co or Fe) and nonferromagnetic metal (such as Ag) become spontaneously arranged laterally on the template layer during co-deposition, such as during ultrahigh vaccum evaporation, and are aligned so that the direction of compostion modulation, i.e., the direction perpendicular to the alternating stripes is along one of the unique axes of the template layer and in a plane parallel to the template layer. A crystalline base layer may be used beneath the template layer to enhance the growth of the template layer. If the template layer is (110) Mo, then the base layer may be sapphire having its (112 bar 0) plane parallel to the (110) Mo plane.

Method for forming a lateral giant magnetoresistance multilayer for a

A method for forming a chemically-ordered ferromagnetic or antiferromagnetic metal alloy film allows the temperature and/or time required for annealing to be reduced. The ferromagnetic or antiferromagnetic metal alloy film is dosed with hydrogen either during or subsequent to deposition of the film on a substrate. The metal alloy film is then heated to desorb the hydrogen atoms from the metal alloy. In one embodiment for dosing the metal alloy film with hydrogen a transition metal of the type that catalyzes the dissociative chemisorption of H.sub.2, such as palladium (Pd), is deposited as a film in contact with the metal alloy film. The Pd film is then heated and while at an elevated temperature, it is exposed to H.sub.2 gas. The H.sub.2 becomes dissociated into hydrogen atoms and the hydrogen atoms become chemically absorbed by the Pd film. During subsequent cooling of the Pd film hydrogen atoms in the Pd film become absorbed into the metal alloy film. When the metal alloy film is annealed the hydrogen atoms become desorbed.

Method for making a chemically-ordered magnetic metal alloy film

A pointing system for controlling a cursor on a computer display device includes a single control actuator that ordinarily controls movement of the cursor on the display device and also detects if an applied cursor force matches a predetermined tap signature. If the applied force substantially matches the predetermined tap signature, then the system responds to the applied force by initiating one or more display actions rather than by moving the display cursor. The system detects tap signature forces applied along the x, y, and z axes of the control actuator and responds by retrieving a cursor context comprising a window display and corresponding cursor location from a queue and opening the associated window. That is, the system changes the active window from among windows of a graphical user interface, preserving the cursor position within each window. Other tap signature responses can correspond to functions initiated by programmable function keys or to user-defined functions. The force signature needed to initiate the display actions comprises a short duration, low level of force, such as a tap on the cursor control actuator that defines a sawtooth-type pulse having a rapidly rising leading edge and a slower failing trailing edge. Off-axis forces, which cannot be detected as occurring primarily along one of the three axes, are ignored to prevent. inadvertent, undirected bumping of the control actuator from initiating unwanted action.

Enhanced program access in a graphical user interface

An environmental interface for a semiconductor electro-optical conversion device layer that is optically transparent, electrically conductive and chemically passivating, made of an elemental semiconductor with an indirect band gap&gt;1 electron volt in a layer between 20 and 200 Angstroms thick. A GaAs covered by GaAlAs converter with a 100 Angstrom Si layer over the GaAlAs is illustrated.

Semiconductor electro-optical conversion

Heterojunction bipolar transistors are disclosed having an energy band offset in the valence or conduction band and the other of the bands being substantially aligned at the heterojunction. For an npn transistor the conduction band is substantially aligned and the bandgap difference is in the valence band. A pnp type transistor is also disclosed wherein all the bandgap difference is in the conduction band and the valence band is substantially aligned. The npn type transistor provides improved hole confinement in the base as well as enhanced electron injection and collection. In one embodiment of a double heterojunction bipolar transistor, materials are selected that utilize Ga compounds in the base and Al and/or In compounds in the emitter and collector, which have a valence band offset of approximately 400 meV or greater and an aligned conduction band at both of the heterojunctions.

Heterojunction bipolar transistor with substantially aligned energy

A method of joining a thermally conductive element to an electric circuit chip for cooling the chip includes initial steps of forming an oxide-free preform of a fusible metal alloy by extrusion of alloy between two mold blocks or plates. During the extrusion, the oxide coating is left behind so that the extruded alloy is essentially free of oxide. The extrusion takes place at a temperature elevated to approximately the liquidus temperature of the alloy. The preform, which may be in the form of a pill or section of thin foil, is placed between interfacing surfaces of the thermally conductive element and the chip, and is then extruded along the interfacing surfaces under pressure and elevated temperature to form a thermally conductive, oxide-free bonding layer of superior thermal conductivity.

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San Jose, CA, United States of America

Ronald Franklin Marks