Bruce A GurneySan Jose, CA

6347049, Feb 12, 2002

Jul 25, 2001

09/916077

Jeffrey R. Childress - San Jose CA
Bruce A. Gurney - San Rafael CA
Markus Schwickert - San Jose CA

International Business Machines Corporation - Armonk NY

G11C 1115

365173, 365171, 365158, 3603242

A low resistance magnetic tunnel junction (MTJ) device has a bilayer or multilayer as the insulating tunnel barrier. In one embodiment the tunnel barrier is a bilayer of a first layer of magnesium oxide on the bottom magnetic electrode and an aluminum oxide layer on the magnesium oxide layer. This bilayer is formed by oxidizing a bilayer of Mg/Al. In a second embodiment the tunnel barrier is a bilayer of first layer of aluminum nitride and a second layer of aluminum oxide on top of the aluminum nitride first layer, with this bilayer formed by oxidizing a bilayer of AlN/Al. MTJ devices with trilayer barriers, such as AlN/Al O /AlN, MgO/Al O /MgO and Al O /MgO/Al O are also possible. The resulting magnetic tunnel junction devices have resistance-area values less than 1000 (m) and preferably in the range of 0. 1 to 100 (m) , making the devices suitable for magnetic read sensors.

6449134, Sep 10, 2002

Aug 5, 1999

09/369076

Robert Stanley Beach - Los Gatos CA
Matthew Carey - San Jose CA
Bruce A. Gurney - San Rafael CA

International Business Machines Corporation - Armonk NY

G11B 5127

36032412

A dual spin valve sensor is provided which is file resettable. An antiparallel (AP) coupled free layer structure is located between first and second pinned layer structures. The AP coupled free layer structure includes an AP coupling layer between first and second AP coupled free layers. When a current pulse is conducted through a sense current circuit the temperature of the sensor increases and conductive layers of the spin valve sensor exert current fields on the first and second pinned structures which set the magnetic spins of first and second antiferromagnetic pinning layers exchange coupled thereto. When the current pulse is terminated or reduced and the sensor cools the first and second pinning layers pin the magnetic moments of the first and second pinned layers antiparallel with respect to each other. Since magnetic moments of the first and second AP coupled free layers are also antiparallel with respect to each other the magnetic moments of the AP coupled free layer structure and the pinned layers are in phase so that a magnetoresistance, one on each side of the AP coupled free layer structure, are additive to provide a dual magnetoresistive effect.

6452761, Sep 17, 2002

Jan 14, 2000

09/483087

Matthew Joseph Carey - San Jose CA
Jeffrey Robinson Childress - San Jose CA
Bruce Alvin Gurney - San Rafael CA
Ren Xu - San Jose CA

International Business Machines Corporation - Armonk NY

G11B 533

360320, 2960313

The current invention provides for magnetic sensor devices with reduced gap thickness and improved thermal conductivity. Gap structures of the current invention are integrated in laminated Magneto-Resistive and Spin-Valve sensors used in magnetic data storage systems. The gap structures are produced by depositing metal layers and oxidizing portions of or all of the metal layers to form thin high quality oxidized metal dielectric separator layers. The oxidized metal layer provides for excellent electrical insulation of the sensor element and any remaining metallic portions of the metal layers provide a thermally conducting pathway to assist the dissipation of heat generated by the sensor element. Because of the combined qualities of electrical insulation and thermal conductivity, magnetic sensor devices of this invention can be made with thinner gap structures and operated at higher drive currents. Further, oxidized metal layers provide suitable surfaces to growing oxidized metal gap insulator layers of any thickness.

6542341, Apr 1, 2003

Nov 18, 1999

09/443039

Matthew Joseph Carey - San Jose CA
Jeffrey Robinson Childress - San Jose CA
Bruce Alvin Gurney - San Rafael CA

International Business Machines Corporation - Armonk NY

G11B 5127

360324

A magnetic sensor which detects an external magnetic field with the aid of a ferromagnetic free layer having a magnetic moment responsive to the external magnetic field. The magnetic sensor has an antiferromagnetic layer which is magnetically exchange-coupled to the free layer to produce an exchange bias field H which acts on the free layer to bias its magnetic moment along a certain orientation such as the transverse direction. The additional exchange bias field H is used in balancing a total transverse internal magnetic field H which is due to other fields generated by the sensor itself. The value of exchange bias field H is set, e. g. , by selecting a certain thickness and a certain composition of the antiferromagnetic layer. The magnetic sensor of the invention can also have a non-magnetic spacer layer interposed between the free layer and the antiferromagnetic layer or be in contact with the free layer. The sensor can be a spin valve sensor, a tunnel valve sensor, or any magnetic sensor using the free layer and the magnetoresistive effect to detect the external magnetic field.

6548186, Apr 15, 2003

May 19, 2000

09/574301

Matthew Joseph Carey - San Jose CA
Bruce Alvin Gurney - San Rafael CA
Robert John Wilson - Saratoga CA

International Business Machines Corporation - Armonk NY

G11B 539

428611, 428668, 428679, 428704, 428693, 428686, 36032412, 338 32 R

In a spin valve, at least one AP pinned sublayer and/or one AP free sublayer comprise high resistivity alloys of the type AB, wherein A is selected from the group consisting of CoFe, NiFe, and CoFeNi, and B is selected from the group consisting of B, Ta, Nb, Zr, and/or Hf. The resistivity value of the highly resistive layer is typically between about 30 -cm and 100 -cm. The highly resistive layers reduce the shunting of the sense current away from the rest of the structure, and prevent electrons from being shunted away from the active region of the spin valve and, thus, reducing R/R. The spin valve of this layered structure can increase the overall sheet resistance and optimize the R/R value of the spin valve.

6594100, Jul 15, 2003

Jul 11, 2001

09/903959

Matthew Joseph Carey - San Jose CA
Eric Edward Fullerton - Morgan Hill CA
Bruce Alvin Gurney - San Rafael CA
Hal Jervis Rosen - Los Gatos CA
Manfred Ernst Schabes - San Jose CA

Hitachi Global Storage Technologies The Netherlands B.V. - Amsterdam

G11B 503

360 66, 428694 TM

A method for writing data on a magnetic recording medium includes providing a magnetic recording layer having at least two ferromagnetic films antiferromagnetically coupled together across a nonferromagnetic spacer film, with one of the ferromagnetic films having a greater magnetic moment than the other. A positive write field is applied to a first region to align the moments of both ferromagnetic films with the positive field, and then a negative write field is applied to an adjacent region to align the moments of both ferromagnetic films with the negative field. When the medium is moved away from the write fields, the moment of the ferromagnetic film with the lesser moment in each region flips to be antiparallel to the moment of the other ferromagnetic film in its region. The result is that the adjacent regions become adjacent magnetized domains with the transition between the domains representative of the written data.

6686068, Feb 3, 2004

Feb 21, 2001

09/791510

Matthew Joseph Carey - San Jose CA
Jeffrey Robinson Childress - San Jose CA
Bruce Alvin Gurney - San Rafael CA

International Business Machines Corporation - Armonk NY

G11B 566

428692, 428694 R, 428694 TM, 428694 TS, 428900, 360113, 360319, 360324, 3603241

A CPP magnetoresistive sensor with a spacer layer made of a heterogeneous material, which is composed of conductive grains within a highly resistive matrix, has a high resistance. The conductive grains are typically made of a conductive element or alloy that can operate as a GMR spacer material. The highly resistive matrix is typically made of a highly resistive or insulating element, alloy or compound that will hinder the flow of electrons. The sensing electrical current is passed through the conductive grains, which are typically made of the same material as GMR spacers, so the GMR is maintained even though the overall resistance is increased.

6721144, Apr 13, 2004

Jan 4, 2001

09/755556

Matthew Joseph Carey - San Jose CA
Hoa Van Do - Fremont CA
Robin Frederick Charles Farrow - San Jose CA
Bruce Alvin Gurney - San Rafael CA
David Thomas Margulies - Gilroy CA
Ronald Franklin Marks - San Jose CA
Philip Milton Rice - San Jose CA
Ren Xu - San Jose CA

International Business Machines Corporation - Armonk NY

G11B 539

36032411, 3603242

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.